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S100B / Protein S100-B · IHC design guide
Design Immunohistochemistry for S100B
Plan chromogenic IHC on paraffin sections using the nuclear and cytoplasmic S100B pattern seen in CNS glia and peripheral nerves (HPA tissue IHC). This guide covers specimen handling, staining controls and interpretation.
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
S100B Immunohistochemistry Experimental Design Guide
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before staining
| Expected localisation | Nuclear and cytoplasmic tissue staining (HPA tissue IHC) | |
| Staining pattern | Nuclear and cytoplasmic staining in CNS, nerves and adipocytes (HPA tissue IHC) | |
| Antigen retrieval | Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen) | |
| Positive control | Breast+4 more · see all | |
| Negative control | Adrenal gland+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image M00979-1) | |
| Caveat | Secretion may complicate tissue RNA–protein correlation (HPA tissue IHC) | |
| Regulation | Expression regulation not specified (UniProt) | |
| Isoform / epitope | No isoforms listed; mature chain spans residues 2–92 (UniProt) |
Section 1
Recommended S100B IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol with four published S100B IHC workflows (PMC4003764; PMC1769505; PMC10906296; PMC5339465).
| Sample | Paraffin-embedded Rat cerebral cortex tissue; fixative not specified (datasheet M00979-1) |
| Fixation | Image fixative and duration unreported (datasheet M00979-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in Tris-EDTA buffer, pH 9.0, 20 min at 95–98 °C (standard rule: nuclear antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit monoclonal (clone BCB-19) anti-S100B, 1:50 recommended; image 1:500 (datasheet M00979-1) |
| Primary incubation | Overnight at 4 °C (standard) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | S100B-positive staining in myoepithelial cells of breast (HPA tissue IHC: High). HPA tissue profile: Nuclear and cytoplasmic expression mainly in CNS, peripheral nerves, adipocytes and subset of lymphoid cells. No signal in the no-primary control. |
💡Decision noteStart with the page’s Tris-EDTA pH 9.0 retrieval at 95–98 °C for 20 min; the human brain protocol offers citrate pH 6.0 as a published alternative (PMC1769505).
Section 2
What Is the Expected S100B Staining Pattern?
S100B can localize to the cytoplasm and nucleus and can be secreted; it has no transmembrane segment (UniProt P04271). In tissue sections, expect nuclear and cytoplasmic staining chiefly in CNS glia and peripheral nerves, with staining also reported in adipocytes and selected other cells (HPA: tissue IHC profile). HPA rates its tissue staining evidence Enhanced, while noting medium consistency with RNA data and a complex RNA–protein relationship for a secreted protein (HPA: tissue IHC reliability).
| Strong nuclear and cytoplasmic staining in glial cells of cerebral cortex, caudate or hippocampus (HPA: High in glial cells). | This fits the reported tissue pattern and UniProt localization (HPA: tissue IHC profile; UniProt P04271). Judge the signal by cell identity and compartment together: staining elsewhere on the section does not establish a positive glial result. HPA’s Enhanced rating supports the pattern, but its stated RNA–protein consistency is medium (HPA: tissue IHC reliability). |
| High staining in cerebellar Bergmann glia, especially cytoplasm or membrane, or in a peripheral nerve (HPA: High in both). | These are reported positive structures (HPA: cerebellum and soft tissue IHC). The Bergmann glia description is specific to cerebellum; it does not make isolated membrane staining in every tissue an expected S100B pattern. Compare morphology and the paired nuclear or cytoplasmic distribution before scoring an unfamiliar structure (HPA: tissue IHC profile). |
| A membrane-only outline or staining confined to an unexpected compartment, without the expected cellular pattern (HPA: tissue IHC profile). | Treat this as a possible artifact or nonspecific signal and recheck morphology, controls and detection. UniProt lists cytoplasm, nucleus and secretion, with no transmembrane segment (UniProt P04271); secretion alone does not validate a crisp cell-surface outline. HPA’s cerebellar Bergmann glia entry is a tissue-specific cytoplasm/membrane observation (HPA: cerebellum IHC). |
| Prominent staining in cells expected to lack S100B, such as adrenal glandular cells or bronchial respiratory epithelium (HPA: Not detected). | Check for antibody cross-reactivity or endogenous detection activity before calling these cells positive. HPA reports those particular cell populations as not detected; it does not classify every cell in either organ as negative (HPA: adrenal gland and bronchus IHC). Compare a no-primary control and the morphology of an established positive structure (general IHC practice). |
| A uniform haze across many cells, or no stain in an established positive structure (HPA: High in CNS glia and peripheral nerve). | Diffuse haze weakens a cell-specific interpretation; absent staining in an HPA-positive structure raises a sensitivity or run-control concern (HPA: tissue IHC). Check background controls for the former and the validated staining workflow for the latter (general IHC practice). Neither observation, by itself, demonstrates a target-specific fixation effect; none is documented in the supplied sources. |
💡Expected S100B appearanceCall a result positive when the appropriate glial cells or peripheral nerve show clear nuclear and/or cytoplasmic staining, often high in the HPA-listed positive structures; uniform haze or strong staining in an HPA-listed negative cell population is suspect (HPA: tissue IHC profile and levels; UniProt P04271).
| Which tissue provides an interpretable positive comparison? | Cerebral cortex, caudate and hippocampus contain glial cells scored High; cerebellar Bergmann glia and soft-tissue peripheral nerve are also High (HPA: tissue IHC). Confirm the named cell type on the slide, since a tissue label alone does not identify which cells should stain (HPA: tissue IHC cell-level entries). |
| How should a negative comparison be chosen? | Adrenal glandular cells and bronchial respiratory epithelial cells are reported Not detected (HPA: tissue IHC). Use those named populations when assessing unexpected staining; do not infer that an entire adrenal gland or bronchus is uniformly negative from a cell-level entry (HPA: tissue IHC). |
| Does antibody validation settle an unusual pattern? | Three listed antibodies have Enhanced IHC status: HPA015768, CAB000073 and CAB078196 (HPA: antibody validation). Enhanced reflects reproduction by independent antibodies or orthogonal data, but HPA also reports medium staining–RNA consistency for S100B (HPA: IHC validation and reliability). Resolve an unusual compartment or cell type with controls and morphology rather than treating the rating as proof for that observation. |
| Can secreted S100B explain extracellular color? | UniProt lists S100B as secreted and says interaction with CLSTN3beta promotes secretion into medium (UniProt P04271). HPA warns that protein and RNA tissue locations may differ for a secreted variant (HPA: reliability description). Extracellular color is therefore a cautious observation, not sufficient evidence of cell-specific expression without the expected stained cells and clean controls. |
| What should an IF/ICC result look like? | HPA’s separate ICC-IF data place S100B mainly in vesicles, cytosol and primary cilium; cilium localization is marked uncertain, while nucleoplasm is an additional supported location (HPA: subcellular ICC-IF). These cell-imaging annotations can guide interpretation of an IF/ICC image, but they do not replace the tissue IHC pattern or define a paraffin-section protocol (HPA: subcellular ICC-IF; HPA: tissue IHC). |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in cerebral cortex, caudate or hippocampal glia (HPA: High in glial cells). | A failed staining run or insufficient assay sensitivity is possible; the slide alone cannot identify a target-specific fixation effect (general IHC practice; HPA: tissue IHC). | Verify the positive-control section and catalog antibody’s IHC-P instructions, then review the run’s antigen retrieval, primary dilution and detection steps as general IHC checks. No S100B-specific retrieval or dilution value is supplied here. |
| No signal in the intended positive tissue, while another structure stains. | The stained structure may differ from the HPA-listed cell population; tissue-level presence does not make every cell positive (HPA: tissue IHC cell-level entries). | Locate the expected glial cells, Bergmann glia or peripheral nerve by morphology and score those cells specifically (HPA: tissue IHC). Use a known-positive control section to distinguish a cell-selection problem from a weak run (general IHC practice). |
| Broad, pale chromogenic color obscures cell boundaries. | Nonspecific background or detection background may be contributing; a diffuse haze does not match HPA’s cell-specific tissue descriptions (HPA: tissue IHC profile; general IHC practice). | Inspect a no-primary control and review blocking, washes, antibody dilution and chromogen development under the validated workflow (general IHC practice). Re-score only where individual cells and compartments remain distinguishable (HPA: tissue IHC profile). |
| Adrenal glandular or bronchial epithelial cells stain strongly (HPA: Not detected). | Cross-reactivity or endogenous detection activity is possible (general IHC practice). HPA’s negative calls apply to these named cell types, not every neighboring structure (HPA: tissue IHC). | Compare the no-primary control and an HPA-positive tissue; inspect morphology before assigning the signal to the named negative cells (general IHC practice; HPA: tissue IHC). If background persists, review the detection system’s endogenous-activity blocking step (general IHC practice). |
| Signal is mainly an isolated membrane rim or extracellular deposit. | S100B lacks a transmembrane segment and can be secreted, so location alone cannot establish cellular S100B expression (UniProt P04271). | Check for accompanying nuclear or cytoplasmic staining in expected cells and compare background controls (HPA: tissue IHC profile; general IHC practice). Interpret cerebellar Bergmann glia in their tissue context, where HPA reports cytoplasm/membrane staining (HPA: cerebellum IHC). |
| An IF/ICC image shows puncta or ciliary signal that differs from the IHC slide. | HPA’s ICC-IF compartment annotations come from cell imaging; primary-cilium localization is marked uncertain (HPA: subcellular ICC-IF). | Assess IF/ICC against its separate guide and controls, and score the paraffin IHC section against tissue cell types and compartments (HPA: subcellular ICC-IF; HPA: tissue IHC). Do not transfer an ICC-IF location into an IHC positive call solely because it appears in the cell image. |
Experiment evidence
IHC & IF images showing S100B staining
M00979-1 · IHCImmunohistochemical analysis of paraffin-embedded Rat cerebral cortex, using the Antibody at 1:500 dilution.
M00979-1 · IHCImmunohistochemical analysis of paraffin-embedded Mouse pancreas, using the Antibody at 1:500 dilution.
M00979-1 · IFImmunofluorescent analysis using the Antibody at 1:50 dilution.
M00979-4 · IHCHuman colon was stained with anti-S100B rabbit antibody
M00979-4 · IHCHuman liver was stained with anti-S100B rabbit antibody
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000160307-S100B/tissue/cerebral+cortex#imid_20161773
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000160307-S100B/tissue/colon#imid_20161691
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000160307-S100B/tissue/liver#imid_20161700
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000160307-S100B/tissue/kidney#imid_20161701
HPA · ICC-IF SK-MEL-30Human Protein Atlas immunofluorescence, SK-MEL-30, antibody HPA015768; green = S100B, blue = nucleus, red = microtubules.
HPA · ICC-IF SK-MEL-30Human Protein Atlas immunofluorescence, SK-MEL-30, antibody HPA015768; green = S100B, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for S100B IHC & IF
🧪Run cerebellum first: Bergmann glia must stain, with cytoplasmic or membrane signal (HPA: High in cerebellar Bergmann glia). Run adrenal gland as the negative tissue (HPA: glandular cells Not detected); on the cerebellar slide, cells outside the Bergmann glia should provide an internal background reference, without assuming every other cell type is negative.
Positive control tissue: Breast (Myoepithelial cells, HPA High)
Negative control tissue: Adrenal gland (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show S100B in SK-MEL-30, U-251MG, U2OS, ASC52telo, RPTEC/TERT1, hTERT-RPE1 (serum starved), with annotated localisation: Vesicles (approved), Primary cilium (uncertain), Cytosol (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control; an isotype control matched to the primary antibody’s host species, immunoglobulin class and clonality where applicable; and S100B knockout tissue or an immunogen peptide competition control if available (standard IHC specificity controls). Quench endogenous peroxidase for chromogenic detection, and check cerebellar autofluorescence if assessing IF (standard IHC/IF practice).
⚠️Feasibility: A target-specific fixation window and retrieval dependency are unreported in the supplied evidence; optimize retrieval empirically (supplied evidence; standard IHC practice). The selected M00979-1 caption shows paraffin-section staining of rat cerebral cortex at 1:500, but reports no fixative, so it does not establish fixation (selected-SKU tissue-IHC caption). The evidence does not establish whether frozen sections or IF are easier; brain autofluorescence can complicate IF interpretation (standard IF practice). The selected M00979-1 tissue-IHC caption documents paraffin sections, but does not specify the fixative (selected-SKU IHC image M00979-1).
HPA tissue IHC evidence for S100B
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. At least one protein variant secreted, tissue location of RNA and protein might differ and correlation is complex.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Breast | Myoepithelial cells | High | Protein (IHC) | HPA → |
| Caudate | Glial cells | High | Protein (IHC) | HPA → |
| Cerebellum | Bergmann glia - cytoplasm/membrane | High | Protein (IHC) | HPA → |
| Cerebral cortex | Glial cells | High | Protein (IHC) | HPA → |
| Hippocampus | Glial cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
| Cervix | Glandular cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced S100B IHC Tips
Troubleshoot S100B staining in paraffin sections by checking retrieval, cellular localisation and controls before comparing chromogenic signal across samples.
What retrieval should I use if S100B staining is weak in paraffin sections?
Use Tris-EDTA pH 9.0 HIER at 95–98 °C for 20 min (page retrieval rule). Check that sections remain attached, cool them consistently after heating, and compare the same retrieval cycle across runs (standard IHC practice). Include a glial-rich positive section, such as cerebral cortex, to distinguish a failed retrieval run from a low-expressing test region (HPA: High in cerebral cortex glial cells). The catalog image shows staining in paraffin-embedded rat cerebral cortex at 1:500, but its caption does not report a retrieval method or fixative (M00979-1 caption).
Could fixation explain weak or uneven S100B staining?
Target-specific fixation sensitivity is unknown: the selected IHC caption identifies paraffin-embedded rat cerebral cortex but does not state its fixative (M00979-1 caption). Record the fixative, fixation duration and section age for each specimen, then compare sections processed together under the same retrieval conditions (standard IHC practice). If tissue history varies, first assess morphology and staining in a positive control before changing antibody concentration (standard IHC practice). Use the page’s Tris-EDTA pH 9.0, 95–98 °C, 20 min retrieval as a consistent starting point; neither tissue expression patterns nor S100B topology establish a fixation effect (page retrieval rule; UniProt P04271 topology).
Should S100B signal be nuclear, cytoplasmic or extracellular?
Assess nuclear and cytoplasmic staining in the appropriate cells: both compartments are reported for S100B in tissue, mainly within CNS and peripheral nerves (HPA tissue IHC profile). Cytoplasmic signal is plausible in glia, while nuclear signal alone should be checked against morphology and controls before scoring (HPA: High in cerebral cortex glial cells; UniProt P04271 subcellular location). S100B is also secreted, so extracellular colour cannot by itself identify the producing cell (UniProt P04271 subcellular location). Record nuclear and cytoplasmic scores separately, using the same counterstain and chromogen exposure across sections (standard IHC practice).
How can epitope choice affect the specificity of S100B IHC?
The supplied protein record lists 0 isoforms and two EF-hand regions, at residues 13–48 and 49–84 (UniProt P04271 isoforms and domains). Its amino-terminal serine can be blocked or acetylated, so an antibody directed there could behave differently from one recognising an internal region; the catalog antibody’s epitope is not supplied (UniProt P04271 modified residues; supplied product evidence). S100B can participate in dimers containing beta chains or an alpha and a beta chain, making antibody specificity important when interpreting closely related S100 staining (UniProt P04271 subunit). Compare an appropriate positive section with a low-expression cell population and consult documented epitope information before assigning unexpected staining to S100B (HPA tissue IHC; standard IHC practice).
How should I check S100B localisation with a separate IF experiment?
For the separate IF/ICC workflow, multiplex S100B with a validated glial marker when examining CNS cells, and inspect single-channel images before interpreting overlap (HPA: High in cerebral cortex glial cells; standard IF practice). Select fluorophores after measuring tissue autofluorescence in unstained controls, favouring a channel with clear separation from that background (standard IF practice). S100B has no transmembrane segment and is reported in cytoplasm and nucleus, so assess permeabilisation when the antibody must access an intracellular epitope (UniProt P04271 topology and subcellular location). Verify the antibody’s IF/ICC suitability and fixation conditions independently; the paraffin-section caption supplies neither IF validation nor fixation evidence (M00979-1 caption).
How do I distinguish diffuse S100B staining from chromogenic background?
Start with a no-primary control and examine whether colour persists in the same structures; persistent colour points to a detection or tissue-background problem (standard IHC practice). Apply a peroxidase block for an enzyme-based DAB workflow, then check reagent blanks and wash consistency before increasing the primary antibody (standard IHC practice). Compare suspected signal with cell morphology: S100B is reported in glial cells and can occur in both nucleus and cytoplasm (HPA: High in cerebral cortex glial cells; HPA tissue IHC profile). The catalog image used 1:500 in paraffin-embedded rat cerebral cortex, which is a documented image condition rather than a proven optimum for other sections (M00979-1 caption).
What should I measure when comparing S100B IHC across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the anatomical region and cell population before scoring, because S100B tissue staining spans glia, peripheral nerves and other cell types (HPA tissue IHC profile). For cellular staining, report the percentage of positive cells and an intensity-based H-score from 0–300, with nuclear and cytoplasmic results separated (standard IHC scoring practice; HPA tissue IHC profile). If counting positive profiles, express density per mm² of evaluable tissue and exclude folds, edges and damaged areas using consistent rules (standard IHC practice). Normalise comparisons to the same eligible cell population or tissue area, and hold retrieval, chromogen development and image thresholds constant across sections (standard IHC practice).
When is an apparent S100B-positive region convincing?
Look for staining that follows intact cells and expected compartments, especially glial cells in cerebral cortex, rather than colour confined to section edges or necrotic areas (HPA: High in cerebral cortex glial cells; standard IHC practice). Nuclear and cytoplasmic signal can both fit the reported tissue profile, whereas an unexpected cell population needs independent validation before biological interpretation (HPA tissue IHC profile). Check a no-primary control for residual enzyme-associated colour and compare the suspected region with a concurrently stained positive section (standard IHC practice). Because S100B may be secreted, extracellular staining alone does not establish which nearby cells produced it (UniProt P04271 subcellular location).
Boster reagents
Best S100B / Protein S100-B IHC Antibodies
Two anti-S100B antibodies have tissue IHC images and list human, mouse and rat reactivity; M00979-1 also has IF images (catalog reactivity; IHC/IF image captions).
Real IHC data
Anti-S100B/S100 Beta Rabbit Monoclonal Antibody
Cat # M00979-1
Real IHC data
Anti-S100B Rabbit Monoclonal Antibody
Cat # M00979-4
M00979-1 lists IHC and ICC/IF applications, with IHC images of rat cerebral cortex, mouse pancreas and hippocampus, and human testis cancer, plus IF images (catalog applications; IHC/IF image captions). M00979-4 lists IHC and IF applications, with IHC images of human liver and human, mouse and rat colon; no IF image is supplied (catalog applications; IHC/IF image captions).
Which to pick: For paraffin-section IHC, choose M00979-1 when its rat cerebral cortex example is relevant; the caption specifies paraffin embedding but does not report the fixative (M00979-1 IHC image caption). For IF/ICC, choose M00979-1 because both applications and IF images are listed, while M00979-4 lists IF but supplies no IF image (catalog applications; IF image captions). For cross-species tissue IHC, M00979-4 has colon images from human, mouse and rat; its captions do not report processing or fixation, and both products are rabbit monoclonals listed as reactive with all three species (M00979-4 IHC image captions; catalog host, clonality and reactivity).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P04271 (S100B_HUMAN, Protein S100-B).
- Human Protein Atlas. S100B tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. S100B subcellular location (ICC-IF): Mainly localized to vesicles, cytosol and primary cilium. In addition localized to the nucleoplasm, microtubules, cytokinetic bridge, mitotic spindle and basal body..
- Human Protein Atlas. S100B antibody validation summary (3 antibodies).
- Synchronized dual pulse gastric electrical stimulation induces activation of enteric glial cells in rats with diabetic gastroparesis. Gastroenterology research and practice 2014 — PMC4003764.
- Evidence for a wide extra-astrocytic distribution of S100B in human brain. BMC neuroscience 2007 — PMC1769505.
- Bone marrow stem cells with or without superparamagnetic iron oxide nanoparticles as a magnetic targeting tool: Which is better in regeneration of neurolysed facial nerve? An experimental study. Heliyon 2024 — PMC10906296.
- Decreased S100B expression in chronic liver diseases. The Korean journal of internal medicine 2017 — PMC5339465.
- PubMed PMID:2394738 — UniProt-cited evidence.
- PubMed PMID:10830953 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for S100B (Protein S100-B). Expected localisation Nuclear and cytoplasmic tissue staining (HPA tissue IHC). Antigen retrieval: Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen). Validated IHC antibody: M00979-1 at 1:50 recommended; image 1:500 (the product's own IHC validation image is shown). Controls (HPA): positive Breast (Myoepithelial cells); negative Adrenal gland. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Paraffin-embedded Rat cerebral cortex tissue; fixative not specified (datasheet M00979-1); 2. Fixation: Image fixative and duration unreported (datasheet M00979-1); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat-induced epitope retrieval in Tris-EDTA buffer, pH 9.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit monoclonal (clone BCB-19) anti-S100B, 1:50 recommended; image 1:500 (datasheet M00979-1); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image M00979-1); Caveat: Secretion may complicate tissue RNA–protein correlation (HPA tissue IHC); Isoform / epitope: No isoforms listed; mature chain spans residues 2–92 (UniProt); Regulation: Expression regulation not specified (UniProt). Evidence: UniProt P04271, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to vesicles, cytosol and primary cilium. In…, Datasheet M00979-1, PMC4003764, PMC1769505. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/S100B/immunohistochemistry-ihc-guide.