This website uses cookies to ensure you get the best experience on our website.
- Table of Contents
ABL2 / Tyrosine-protein kinase ABL2 · IHC design guide
Design Immunohistochemistry for ABL2
Plan chromogenic ABL2 IHC in paraffin sections with the catalog antibody at 2–5 μg/mL (datasheet PB9913). Expect general nuclear staining in tissue IHC (HPA tissue IHC), while interpreting its uncertain reliability alongside the cytoplasmic and cytoskeletal annotation (HPA tissue IHC; UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
ABL2 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 | Observed nuclear (HPA tissue IHC); annotated cytoplasm/cytoskeleton (UniProt) | |
| Staining pattern | General nuclear staining across tissues (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet PB9913) | |
| Positive control | Appendix+4 more · see all | |
| Negative control | None in HPA (detected in all 45 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation conditions consistent. (standard IHC practice; not target-specific) | |
| Caveat | Tissue IHC reliability is uncertain amid splice/transcript discrepancies (HPA tissue IHC) | |
| Regulation | Expression regulation is not specified (UniProt) | |
| Isoform / epitope | 9 isoforms; epitope coverage is unknown (UniProt) |
Section 1
Recommended ABL2 IHC & IF Protocols
The catalog antibody protocol (datasheet PB9913) is followed by three published ABL2 IHC protocols (PMC4051810; PMC9818720; PMC10540884).
| Sample | Paraffin-embedded human gallbladder carcinoma tissue; fixative not specified (datasheet PB9913) |
| Fixation | Image fixative and duration unreported (datasheet PB9913); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet PB9913); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet PB9913) |
| Primary antibody | Rabbit anti-ABL2, 2-5μg/ml (datasheet PB9913) |
| Primary incubation | Overnight at 4 °C (datasheet PB9913) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet PB9913) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | ABL2-positive staining in glandular cells of appendix (HPA tissue IHC: Medium). HPA tissue profile: General nuclear expression. No signal in the no-primary control. |
💡Decision noteStart with EDTA pH 8.0 heat retrieval for the catalog antibody (datasheet PB9913). To reproduce a published protocol, use that article’s stated retrieval condition (PMC4051810; PMC9818720; PMC10540884).
Section 2
What Is the Expected ABL2 Staining Pattern?
ABL2 is a cytoplasmic, cytoskeleton-associated protein with no transmembrane segment (UniProt P42684: subcellular location and topology). In paraffin sections, HPA reports a general nuclear staining pattern, including medium staining in appendix glandular cells and bone marrow hematopoietic cells (HPA: tissue IHC). Interpret that nuclear pattern cautiously: HPA rates its IHC reliability Uncertain and notes a splice or transcript discrepancy and evidence for several subcellular locations (HPA: reliability description).
| Defined nuclear staining in appendix or breast glandular cells, or bone marrow hematopoietic cells. | This resembles HPA's medium IHC staining and general nuclear profile (HPA: tissue IHC). It is a plausible slide result, but nuclear localisation alone does not establish ABL2 specificity: all three listed IHC antibodies are rated Uncertain (HPA: antibodies). |
| Cytoplasmic or cytoskeleton-associated staining in identifiable cells. | This fits UniProt's cytoplasm and cytoskeleton annotation (UniProt P42684: subcellular location). HPA ICC-IF places ABL2 mainly in the cytosol, with additional intermediate-filament localisation (HPA: subcellular). Compare it with the nuclear IHC report rather than rejecting either compartment on sight. |
| A sharp cell-surface rim, extracellular deposit, or signal detached from identifiable cells. | An exclusively membrane-like or extracellular pattern is poorly supported for a protein with no transmembrane segment and a cytoplasmic/cytoskeletal annotation (UniProt P42684: topology and subcellular location). Treat it as a possible detection artefact and check controls before assigning it to ABL2 (standard IHC practice). |
| Strong staining confined to a cell population reported as low, such as lung alveolar cells or liver cholangiocytes. | This conflicts with HPA's low staining in those cells (HPA: tissue IHC). Consider cross-reactivity or endogenous detection activity, especially if the signal persists in a no-primary control (standard IHC practice). HPA's uncertain IHC reliability prevents treating this mismatch alone as proof of a false positive (HPA: reliability). |
| Diffuse colour across cells and tissue spaces, or no staining in an appendix or bone marrow section. | Diffuse signal without cell boundaries limits compartment scoring and calls for background controls (standard IHC practice). An absent result in tissue with reported medium staining warrants a technical check, but HPA's medium rating is a reported observation, not a guarantee for every section (HPA: tissue IHC and reliability). |
💡Expected ABL2 appearanceA defensible positive IHC result is cell-associated staining in identifiable glandular or hematopoietic cells at approximately HPA's reported medium level, scored with its reported nuclear pattern and the cytoplasmic/cytoskeletal evidence in view; diffuse extracellular colour or an isolated sharp membrane rim is suspect (HPA: tissue IHC and reliability; UniProt P42684: location and topology; standard IHC practice).
| Compartment evidence | HPA reports general nuclear tissue IHC staining but rates that IHC profile Uncertain; UniProt annotates cytoplasm/cytoskeleton, while HPA ICC-IF approves cytosol and intermediate filaments (HPA: tissue IHC, antibodies and subcellular; UniProt P42684: location). Record nuclear and cytoplasmic staining separately. |
| Choice of tissue and cells | Appendix glandular cells, bone marrow hematopoietic cells, and bronchus respiratory epithelial cells have reported medium staining; thyroid glandular cells, lung alveolar cells, and pancreas exocrine glandular cells are reported low (HPA: tissue IHC). These are comparison levels, not absolute positive or negative controls. |
| Antibody validation | HPA rates the IHC result Uncertain for HPA001866, HPA072754, and CAB017106; HPA072754 has Approved ICC status (HPA: antibodies). ICC approval supports its cell-imaging localisation assessment but does not upgrade its IHC rating. |
| Isoforms and epitope | UniProt lists nine ABL2 isoforms and SH3, SH2, and kinase domains (UniProt P42684: isoforms and domains). An antibody's epitope would determine which isoforms or domain-containing forms it detects; no epitope is supplied here, so do not infer coverage. |
| Processing and topology | UniProt reports no signal peptide, propeptide, or transmembrane segment, and describes the chain as residues 2–1182 (UniProt P42684: processing and topology). An extracellular or uniformly surface-restricted IHC pattern therefore needs independent support before assignment to ABL2. |
| IF/ICC interpretation | For the separate IF/ICC application, expect mainly cytosolic signal with possible intermediate-filament signal (HPA: subcellular). Those approved ICC-IF locations help interpret compartment differences; they do not supply an IF/ICC protocol or establish the paraffin-section nuclear result as specific (HPA: subcellular and IHC reliability). |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in appendix glandular cells or bone marrow hematopoietic cells. | These cells have medium HPA IHC staining, so absent signal may reflect assay performance or section variation; their staining is not guaranteed (HPA: tissue IHC and reliability). | Check the section and detection controls, then review the catalog antibody's IHC-P dilution and antigen-retrieval instructions if available (standard IHC practice). Do not infer ABL2 absence from one blank section. |
| Only a nuclear signal is visible. | Nuclear staining matches HPA's tissue profile, but that profile is rated Uncertain and differs from UniProt's cytoplasmic/cytoskeletal annotation and HPA's approved ICC-IF locations (HPA: tissue IHC, reliability and subcellular; UniProt P42684: location). | Score its cell type, distribution, and no-primary control; describe it as an HPA-like IHC pattern with unresolved compartment specificity (HPA: tissue IHC and reliability; standard IHC practice). |
| Cytoplasmic staining appears without a clear nuclear signal. | Cytoplasmic localisation is supported by UniProt and HPA ICC-IF, despite HPA's general nuclear tissue IHC profile (UniProt P42684: location; HPA: subcellular and tissue IHC). | Record the compartments separately and compare staining across the reported medium and low cell populations; avoid declaring the cytoplasmic signal wrong solely because the tissue IHC profile is nuclear (HPA: tissue IHC and reliability). |
| Strong signal appears mainly in HPA low-staining cells. | The cell distribution differs from the reported low levels and may reflect cross-reactivity or endogenous chromogenic detection activity (HPA: tissue IHC; standard IHC practice). | Compare an adjacent no-primary section and the reported medium-staining cell populations; investigate persistent background before interpreting the low-cell signal as ABL2 (HPA: tissue IHC; standard IHC practice). |
| Colour is diffuse or remains in the no-primary control. | A signal that does not require primary antibody is consistent with background or endogenous detection activity (standard IHC practice). | Review blocking, washing, chromogen exposure, and the detection-system controls; rescore only signal that remains cell-associated above the control (standard IHC practice). |
| A crisp rim is interpreted as cell-surface ABL2. | A surface-only assignment conflicts with the absence of a transmembrane segment and the cytoplasmic/cytoskeletal location annotations (UniProt P42684: topology and location). | Check whether the rim also appears in controls or follows tissue edges, then report the observed pattern without assigning it to ABL2 unless independently supported (standard IHC practice; UniProt P42684: topology). |
Experiment evidence
IHC & IF images showing ABL2 staining
PB9913 · IHCIHC analysis of ABL2 using anti-ABL2 antibody (PB9913). ABL2 was detected in a paraffin-embedded section of human gallbladder carcinoma tiss
PB9913 · IHCIHC analysis of ABL2 using anti-ABL2 antibody (PB9913). ABL2 was detected in a paraffin-embedded section of mouse brain tissue. Heat mediate
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000143322-ABL2/tissue/cerebral+cortex#imid_960536
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000143322-ABL2/tissue/colon#imid_958446
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000143322-ABL2/tissue/liver#imid_958439
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000143322-ABL2/tissue/kidney#imid_958440
HPA · ICC-IF PODO/TERT256Human Protein Atlas immunofluorescence, PODO/TERT256, antibody HPA072754; green = ABL2, blue = nucleus, red = microtubules.
HPA · ICC-IF PODO/TERT256Human Protein Atlas immunofluorescence, PODO/TERT256, antibody HPA072754; green = ABL2, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for ABL2 IHC & IF
🧪Run appendix first and assess its glandular cells, which show Medium ABL2 staining (HPA: appendix glandular cells, Medium). HPA detects ABL2 in all 45 scored tissues, so there is no supported negative tissue; use no-primary and isotype controls, and treat any unstained nonglandular cells on the appendix slide as background comparators rather than confirmed ABL2-negative cells (HPA: no negative rows; ABL2 detected in all 45 scored tissues).
Positive control tissue: Appendix (Glandular cells, HPA Medium)
Negative control tissue: None in HPA: ABL2 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show ABL2 in PODO/TERT256, U-251MG, U2OS, with annotated localisation: Cytosol (approved) (HPA subcellular).
Technical controls: Include a secondary-only section, a concentration- and immunoglobulin-class-matched rabbit IgG isotype control, and ABL2-knockout material processed alongside the positive section as a biological negative (selected PB9913 caption: rabbit primary; standard IHC controls). For appendix IHC, quench endogenous peroxidase and check whether luminal mucus traps chromogen or antibody (standard chromogenic IHC practice).
⚠️Feasibility: The selected PB9913 paraffin-section caption reports heat-mediated retrieval in EDTA at pH 8.0 and primary incubation at 2 μg/mL overnight at 4°C, but its fixative is unreported (selected PB9913 caption). No supplied source reports an ABL2-specific fixation window or fixation effect, and the paraffin caption does not establish fixation (selected PB9913 caption: fixative unreported). There is no basis here to rank frozen sections or IF as easier than paraffin IHC; ICC-IF images show mainly cytosolic ABL2 with additional intermediate-filament localization, while appendix luminal mucus warrants a background check in chromogenic sections (HPA: subcellular localization; standard IHC practice). The selected PB9913 tissue-IHC caption documents paraffin sections, but does not specify the fixative (selected-SKU IHC image PB9913).
HPA tissue IHC evidence for ABL2
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Uncertain — Caution, splice and/or transcript discrepancy exists and external data suggests several subcellular locations.). 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 |
|---|---|---|---|---|
| Appendix | Glandular cells | Medium | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Medium | Protein (IHC) | HPA → |
| Breast | Glandular cells | Medium | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Medium | Protein (IHC) | HPA → |
| Caudate | Glial cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: ABL2 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced ABL2 IHC Tips
Use the paraffin-section IHC evidence as the starting point, then verify ABL2 staining by compartment, cell type, and controls.
Which antigen retrieval should I use when ABL2 staining is weak in paraffin sections?
Start with heat-mediated EDTA pH 8.0 antigen retrieval for paraffin sections (datasheet PB9913). The catalog antibody detected ABL2 in paraffin-embedded human gallbladder carcinoma after this retrieval, followed by 2 μg/ml primary antibody overnight at 4°C (PB9913 tissue-IHC caption). If staining is weak, compare a modest range of heating times while holding buffer, antibody concentration, and detection constant (standard IHC practice). Include a section processed without primary antibody to reveal detection background, and evaluate signal in intact cells rather than damaged section edges (standard IHC practice). The caption does not report a heating time or tissue fixative (PB9913 tissue-IHC caption).
How should I assess whether fixation is suppressing ABL2 staining?
Target-specific fixation sensitivity is unknown because the ABL2 tissue-IHC caption identifies a paraffin section but does not report its fixative (PB9913 tissue-IHC caption). Record the fixative, fixation duration, tissue thickness, and processing history for each specimen before comparing staining (standard IHC practice). Compare matched sections with the same EDTA pH 8.0 retrieval and 2 μg/ml primary antibody conditions used in the reported image (PB9913 tissue-IHC caption). If a fixation effect is suspected, vary one processing factor at a time and judge both staining and tissue morphology against a consistently processed reference section (standard IHC practice). Neither the tissue expression pattern nor ABL2 topology establishes a fixation effect (HPA tissue IHC; UniProt P42684 topology).
Should I accept predominantly nuclear ABL2 staining as specific?
Treat predominantly nuclear chromogen as a result requiring independent validation: the tissue atlas describes general nuclear expression but assigns its IHC profile uncertain reliability (HPA tissue IHC). UniProt places ABL2 in the cytoplasm and cytoskeleton, while approved cell imaging places it mainly in the cytosol with additional intermediate-filament localization (UniProt P42684 subcellular; HPA subcellular). Score nuclear and cytoplasmic staining separately in the same intact cells, using the same counterstain and exposure to DAB across sections (standard IHC practice). Compare the pattern with a no-primary control and an independently validated antibody or orthogonal expression evidence before assigning nuclear signal to ABL2 (standard IHC practice).
Could splice variants or epitope placement explain inconsistent ABL2 staining?
ABL2 has 9 listed isoforms, and the tissue atlas flags a splice or transcript discrepancy that contributes to uncertain IHC reliability (UniProt P42684 isoforms; HPA tissue IHC). Locate the catalog antibody's immunogen within the expressed isoforms before treating a negative section as absence of all ABL2 forms (standard IHC interpretation). Its SH3, SH2, and kinase domains occupy residues 107–167, 173–263, and 288–539, respectively, but the supplied caption gives no antibody epitope (UniProt P42684 domains; PB9913 tissue-IHC caption). Compare independently mapped epitopes or orthogonal expression data, and keep retrieval conditions identical when assessing discrepant staining (standard IHC practice).
How can IF help resolve ambiguous ABL2 staining in tissue?
Use IF as a separate localization check rather than assuming the paraffin IHC conditions transfer directly; the supplied ABL2 image documents chromogenic tissue IHC only (PB9913 tissue-IHC caption). Multiplex ABL2 with a validated marker for the cell population being assessed, such as glandular cells where the atlas reports medium staining (HPA tissue IHC; standard IF practice). Choose a red or far-red fluorophore after checking tissue autofluorescence and single-label controls (standard IF practice). ABL2 has no transmembrane segment and is reported in the cytosol and cytoskeleton, so assess intracellular epitope access with controlled permeabilisation while preserving morphology (UniProt P42684 topology and subcellular; HPA subcellular; standard IF practice).
What should I change if DAB staining is diffuse or widespread?
First compare a no-primary control with the stained section to locate background from the detection system or endogenous tissue activity (standard IHC practice). The reported ABL2 tissue method used 10% goat serum block, a peroxidase-conjugated secondary antibody, and DAB development (PB9913 tissue-IHC caption). Apply an endogenous peroxidase block and check whether DAB develops in the no-primary section; these are general chromogenic IHC controls, not evidence of ABL2 expression (standard IHC practice). If background persists, optimize blocking, washing, primary concentration, and development time one factor at a time while retaining EDTA pH 8.0 retrieval as the starting condition (standard IHC practice; datasheet PB9913).
How should I quantify ABL2 IHC across differently cellular sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring because reported ABL2 localization differs between tissue IHC and cell imaging (HPA tissue IHC; HPA subcellular). For each intact region, record the percentage of positive cells and staining intensity on a 0–3 scale; an H-score sums each intensity multiplied by its percentage, yielding 0–300 (standard IHC practice). Report nuclear and cytoplasmic scores separately, and normalize counts to viable cells or positive-cell density per mm² of viable tissue (standard IHC practice). Use the same retrieval, detection, DAB development, and scoring thresholds across compared sections, with blinded review where feasible (standard IHC practice).
How do I distinguish true ABL2 staining from tissue artefact?
Look for a reproducible cellular pattern in viable tissue, then test whether it survives review of no-primary controls and independently supported expression (standard IHC practice). Cytoplasmic or cytoskeletal staining is compatible with UniProt localization and approved cell imaging, whereas nuclear tissue staining requires extra scrutiny because the atlas calls its IHC reliability uncertain (UniProt P42684 subcellular; HPA subcellular; HPA tissue IHC). Check that the positive cells match the population being scored; the atlas reports medium glandular-cell staining in several tissues but also lists low-staining cell populations (HPA tissue IHC). Exclude section edges, necrotic areas, precipitated DAB, and endogenous enzyme signal before calling a region positive (standard IHC practice).
Boster reagents
Best ABL2 / Tyrosine-protein kinase ABL2 IHC Antibodies
PB9913 has real paraffin-section IHC images from human gallbladder carcinoma and mouse brain (PB9913 IHC captions); no IF/ICC data are provided (catalog: PB9913 applications and images).
Real IHC data
Anti-ABL2 Antibody ®
Cat # PB9913
PB9913 is listed for IHC and for human, mouse, and rat reactivity (catalog: PB9913 applications and reactivity). Its IHC images document paraffin sections of human gallbladder carcinoma and mouse brain (PB9913 IHC captions).
Which to pick: Choose PB9913 for paraffin-section tissue IHC; its captions use 2 μg/ml antibody after EDTA pH 8.0 retrieval, and the fixative is unreported (PB9913 IHC captions). No listed SKU has IF/ICC validation (catalog: PB9913 applications and images). For cross-species work, PB9913 lists human, mouse, and rat reactivity, while its IHC captions document human and mouse sections only (catalog: PB9913 reactivity; PB9913 IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P42684 (ABL2_HUMAN, Tyrosine-protein kinase ABL2).
- Human Protein Atlas. ABL2 tissue IHC expression (reliability: Uncertain).
- Human Protein Atlas. ABL2 subcellular location (ICC-IF): Mainly localized to the cytosol. In addition localized to the intermediate filaments..
- Human Protein Atlas. ABL2 antibody validation summary (3 antibodies).
- Overexpression of Abl2 predicts poor prognosis in hepatocellular carcinomas and is associated with cancer cell migration and invasion. OncoTargets and therapy 2014 — PMC4051810.
- Study of the Regulatory Mechanism of miR-26a-5p in Allergic Asthma. Cells 2022 — PMC9818720.
- Inhibition of Abelson Tyrosine-Protein Kinase 2 Suppresses the Development of Alcohol-Associated Liver Disease by Decreasing PPARgamma Expression. Cellular and molecular gastroenterology and hepatology 2023 — PMC10520367.
- ABL1 and ABL2 promote medulloblastoma leptomeningeal dissemination. Neuro-oncology advances 2023 — PMC10540884.
- PubMed PMID:2198571 — UniProt-cited evidence.
- PubMed PMID:18810762 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for ABL2 (Tyrosine-protein kinase ABL2). Expected localisation Observed nuclear (HPA tissue IHC); annotated cytoplasm/cytoskeleton (UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet PB9913). Validated IHC antibody: PB9913 at 2-5μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Appendix (Glandular cells); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human gallbladder carcinoma tissue; fixative not specified (datasheet PB9913); 2. Fixation: Image fixative and duration unreported (datasheet PB9913); 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 retrieval: EDTA pH 8.0 (datasheet PB9913); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet PB9913); 8. Primary antibody: Rabbit anti-ABL2, 2-5μg/ml (datasheet PB9913); 9. Primary incubation: Overnight at 4 °C (datasheet PB9913). Watch for: Fixation: Keep fixation conditions consistent. (standard IHC practice; not target-specific); Caveat: Tissue IHC reliability is uncertain amid splice/transcript discrepancies (HPA tissue IHC); Isoform / epitope: 9 isoforms; epitope coverage is unknown (UniProt); Regulation: Expression regulation is not specified (UniProt). Evidence: UniProt P42684, HPA tissue IHC · Uncertain, HPA ICC-IF · Mainly localized to the cytosol. In addition localized to the…, Datasheet PB9913, PMC4051810, PMC9818720. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/ABL2/immunohistochemistry-ihc-guide.