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FAM111B / Serine protease FAM111B · IHC design guide
Design Immunohistochemistry for FAM111B
Plan chromogenic FAM111B IHC on paraffin sections using the IHC-validated antibody at 2–5 μg/ml (datasheet A14246-2). Use breast glandular cells as a positive reference and adipocytes as a negative reference, while interpreting cytoplasmic staining cautiously because tissue IHC reliability is uncertain (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FAM111B 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 | Mainly cytoplasmic in several tissues (HPA tissue IHC) | |
| Staining pattern | Mainly cytoplasmic; glandular and lymphoid cells stain (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A14246-2) | |
| Positive control | Appendix+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific) | |
| Caveat | Possible off-target staining; low RNA concordance (HPA tissue IHC) | |
| Regulation | Tissue-enhanced RNA in lymphoid tissue (HPA tissue RNA) | |
| Isoform / epitope | 2 isoforms; verify antibody epitope coverage (UniProt) |
Section 1
Recommended FAM111B IHC & IF Protocols
The catalog antibody’s IHC-P protocol is followed by published FAM111B IHC methods for lung and bladder cancer tissue (PMC7385341; PMC10648174).
| Sample | Paraffin-embedded follicles of human thyroid cancer tissue; fixative not specified (datasheet A14246-2) |
| Fixation | Image fixative and duration unreported (datasheet A14246-2); 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 A14246-2); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A14246-2) |
| Primary antibody | Rabbit anti-FAM111B, 2-5 μg/ml (datasheet A14246-2) |
| Primary incubation | Overnight at 4 °C (datasheet A14246-2) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A14246-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FAM111B-positive staining in lymphoid tissue of appendix (HPA tissue IHC: Medium). HPA tissue profile: Mainly cytoplasmic expression in several tissues. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 for the catalog antibody (datasheet A14246-2). Use citrate retrieval when following the bladder tissue protocol (PMC10648174).
Section 2
What Is the Expected FAM111B Staining Pattern?
For paraffin-section IHC, expect mainly cytoplasmic FAM111B staining in selected lymphoid and glandular cells; the reported positive examples are medium intensity (HPA tissue IHC). ICC-IF instead places FAM111B mainly in the nucleoplasm, with additional cytosol signal (HPA subcellular ICC-IF). FAM111B has no annotated transmembrane segment (UniProt Q6SJ93). Interpret tissue staining cautiously: HPA rates its IHC profile Uncertain and reports presumed off-target binding (HPA tissue IHC).
| Medium cytoplasmic signal in appendix lymphoid tissue or breast, prostate, rectal, epididymal, or small-intestinal glandular cells (HPA tissue IHC). | This matches the reported tissue IHC distribution, provided the signal follows the relevant cells and the negative controls remain clear (HPA tissue IHC; general IHC practice). A matching pattern supports interpretation but does not independently establish antibody specificity: the tissue profile is rated Uncertain (HPA tissue IHC). |
| A strong membrane outline or a compartment pattern unlike the reported mainly cytoplasmic tissue stain (HPA tissue IHC). | Treat this as a possible artefact and check section morphology, background, and controls (general IHC practice). FAM111B has no annotated transmembrane segment (UniProt Q6SJ93). Do not reject nuclear signal solely because tissue IHC is mainly cytoplasmic: nucleoplasm is the approved main ICC-IF location (HPA subcellular ICC-IF). |
| Prominent staining in adipocytes, heart cardiomyocytes, or bronchial respiratory epithelium (HPA tissue IHC). | These sampled cell types were reported as Not detected; unexpected staining raises concern for cross-reactivity or endogenous chromogen activity (HPA tissue IHC; general IHC practice). Check a no-primary control and whether pigment or precipitate persists outside the expected cell pattern (general IHC practice). |
| Diffuse color across multiple cell types, lumens, or tissue-free areas (general IHC practice). | A pattern that ignores cell boundaries is more consistent with background, precipitate, or incomplete blocking than interpretable FAM111B localization (general IHC practice). Do not use its intensity to score cells; compare the no-primary control and inspect the detection reagents (general IHC practice). |
| No signal in appendix lymphoid tissue or a reported medium-positive glandular sample (HPA tissue IHC). | Check tissue preservation, antibody application, retrieval, and detection with appropriate controls before calling the specimen negative (general IHC practice). The HPA examples guide control selection, but its Uncertain IHC reliability means any single positive tissue is an imperfect specificity benchmark (HPA tissue IHC). |
💡Expected FAM111B appearanceA plausible positive is medium, mainly cytoplasmic staining in the specified lymphoid or glandular cells; diffuse background or prominent staining in reported Not detected cell types is suspect, subject to HPA’s Uncertain IHC reliability (HPA tissue IHC; general IHC practice).
| Tissue and cell selection (HPA tissue IHC). | Appendix lymphoid tissue and several specified glandular populations show Medium staining, while several other sampled populations are Not detected (HPA tissue IHC). Score the identified cell population rather than treating every cell in an organ as an equivalent control (general IHC practice). |
| Assay-specific localization: what should IF/ICC show? (HPA tissue IHC; HPA subcellular ICC-IF). | ICC-IF shows mainly nucleoplasm with additional cytosol, whereas tissue IHC is described as mainly cytoplasmic (HPA subcellular ICC-IF; HPA tissue IHC). Interpret each observation within its assay; this IHC section supplies no IF/ICC protocol (general IHC practice). |
| Antibody evidence (HPA antibodies; HPA tissue IHC). | HPA038637 is rated Uncertain for IHC and Approved for ICC; HPA also notes low agreement between tissue staining and RNA data and disregarded presumed off-target binding (HPA antibodies; HPA tissue IHC). Require controls and avoid treating every positive chromogenic signal as verified FAM111B (general IHC practice). |
| Protein topology and processing (UniProt Q6SJ93). | FAM111B has no annotated transmembrane segment or signal peptide, and its annotated chain spans residues 1–734 (UniProt Q6SJ93). These annotations offer no basis to expect a membrane rim or a shed extracellular staining pattern; they do not establish fixation sensitivity or an antibody epitope (UniProt Q6SJ93). |
| Situation | Likely cause | Next action |
|---|---|---|
| Reported positive cells are blank (HPA tissue IHC). | The section, primary-antibody step, retrieval, or chromogenic detection may have failed (general IHC practice). | Run a reported positive tissue alongside the sample; review tissue quality, retrieval conditions, primary application, and detection controls before scoring absence (HPA tissue IHC; general IHC practice). |
| No-primary control develops color (general IHC practice). | Endogenous detection activity, pigment, or a detection-reagent background may contribute (general IHC practice). | Identify the color’s cellular distribution; review the applicable endogenous-activity block and detection reagents, then repeat with the no-primary control (general IHC practice). |
| Color spreads through tissue-free space or masks cell boundaries (general IHC practice). | Reagent precipitate or nonspecific background may obscure cellular staining (general IHC practice). | Inspect reagent quality and washing; repeat with controls and score only cell-associated signal that can be localized confidently (general IHC practice). |
| Strong signal appears in a reported Not detected cell population (HPA tissue IHC). | Cross-reactivity or endogenous chromogenic activity is possible; HPA reports presumed off-target binding (HPA tissue IHC; general IHC practice). | Compare matched no-primary and reported positive tissue controls, then withhold a FAM111B-specific call if the unexpected pattern remains unexplained (HPA tissue IHC; general IHC practice). |
| The stain is chiefly nuclear in a paraffin section (HPA tissue IHC). | The pattern differs from the mainly cytoplasmic tissue IHC profile, although nucleoplasm is the approved main ICC-IF location (HPA tissue IHC; HPA subcellular ICC-IF). | Check morphology and controls, and report the assay and compartment explicitly; do not use ICC-IF localization alone to validate the tissue IHC result (general IHC practice; HPA tissue IHC). |
| A clean-looking positive conflicts with another tissue result (HPA tissue IHC). | The HPA tissue profile has low staining-versus-RNA consistency and an Uncertain reliability rating (HPA tissue IHC). | Recheck cell identity, controls, and the specific tissue pattern; record the discrepancy without upgrading the antibody’s IHC validation status (HPA tissue IHC; general IHC practice). |
Experiment evidence
IHC & IF images showing FAM111B staining
A14246-2 · IHCIHC analysis of FAM111B using anti-FAM111B antibody (A14246-2). FAM111B was detected in a paraffin-embedded section of follicles of human th
A14246-2 · IHCIHC analysis of FAM111B using anti-FAM111B antibody (A14246-2). FAM111B was detected in a paraffin-embedded section of follicles of human th
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000189057-FAM111B/tissue/cerebral+cortex#imid_9901236
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000189057-FAM111B/tissue/colon#imid_9903482
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000189057-FAM111B/tissue/liver#imid_9903475
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000189057-FAM111B/tissue/kidney#imid_9903476
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA038637; green = FAM111B, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA038637; green = FAM111B, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FAM111B IHC & IF
🧪Run appendix first: lymphoid tissue should stain at a medium level (HPA: appendix, lymphoid tissue, Medium). Use adipose tissue as the negative comparator because adipocytes are not detected (HPA: adipose tissue, adipocytes, Not detected); on the appendix slide, cells without visible staining should show only background signal, but their FAM111B status needs independent confirmation (standard IHC practice).
Positive control tissue: Appendix (Lymphoid tissue, HPA Medium)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FAM111B in A-431, U-251MG, U2OS, with annotated localisation: Nucleoplasm (approved) (HPA subcellular).
Technical controls: Include no-primary (secondary-only) and matched rabbit IgG isotype controls, plus a FAM111B knockout sample or peptide competition if a suitable peptide is available (selected-SKU tissue-IHC caption: rabbit primary antibody; standard IHC practice). For HRP/DAB staining of appendix, quench endogenous peroxidase and check background on the no-primary slide (selected-SKU tissue-IHC caption: HRP/DAB; standard chromogenic IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected-SKU paraffin-section caption does not state the fixative (selected-SKU tissue-IHC caption). That caption uses heat retrieval in EDTA at pH 8.0, so assess staining with that retrieval condition; it does not establish that retrieval is required under every condition (selected-SKU tissue-IHC caption). HPA has ICC-IF images in A-431, U-251MG and U2OS, but the supplied evidence does not establish that IF or frozen sections are easier; endogenous peroxidase in appendix lymphoid tissue can complicate HRP/DAB interpretation (HPA: subcellular; standard chromogenic IHC practice).
HPA tissue IHC evidence for FAM111B
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Uncertain — Low consistency between antibody staining and RNA expression data. Pending external verification. Presumed off target binding observed and disregarded.). 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 | Lymphoid tissue | Medium | Protein (IHC) | HPA → |
| Breast | Glandular cells | Medium | Protein (IHC) | HPA → |
| Epididymis | Glandular cells | Medium | Protein (IHC) | HPA → |
| Prostate | Glandular cells | Medium | Protein (IHC) | HPA → |
| Rectum | Glandular cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | 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 → |
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced FAM111B IHC Tips
Troubleshoot FAM111B staining in paraffin sections using the catalog antibody’s reported conditions, with IF/ICC considerations for assay comparison.
What retrieval should I try first if FAM111B staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A14246-2). The catalog antibody’s tissue image used that retrieval, followed by 10% goat serum blocking and 2 µg/mL primary antibody overnight at 4°C (datasheet A14246-2). If staining remains weak, compare a shorter and longer heating period on matched sections while keeping the antibody concentration and DAB development constant (standard IHC practice). Include a section processed without primary antibody, and judge improvement by cell-associated signal and tissue preservation, since the reported image does not establish an optimal heating duration (datasheet A14246-2; standard IHC practice).
Could fixation explain weak or uneven FAM111B staining?
Target-specific fixation sensitivity is unknown: the catalog image identifies a paraffin section but does not state its fixative (datasheet A14246-2). Record the fixative, fixation duration, section thickness and storage conditions for each specimen before comparing staining intensity (standard IHC practice). Run matched sections together using EDTA at pH 8.0, 2 µg/mL primary antibody overnight at 4°C, and the same detection schedule to isolate specimen-processing differences (datasheet A14246-2; standard IHC practice). If morphology or staining varies across a section, inspect processing quality and repeat on another section before assigning the difference to FAM111B expression (standard IHC practice).
Should FAM111B appear in nuclei or cytoplasm by chromogenic IHC?
Score cytoplasmic staining separately from nuclear staining: tissue IHC is described as mainly cytoplasmic, whereas ICC/IF places FAM111B mainly in the nucleoplasm with additional cytosolic localisation (HPA tissue IHC; HPA subcellular). UniProt does not annotate a subcellular location, so neither compartment alone proves antibody specificity (UniProt Q6SJ93). Examine intact cells at a consistent counterstain and DAB exposure, and record each compartment’s intensity and fraction of positive cells (standard IHC practice). If nuclear-only or diffuse extracellular colour dominates, check the no-primary control and compare the pattern with an independently validated reagent before interpreting it as FAM111B (standard IHC practice).
How can an unmapped epitope affect FAM111B IHC results?
FAM111B has 2 annotated isoforms, and the supplied antibody caption does not identify its epitope or establish recognition of both (UniProt Q6SJ93; datasheet A14246-2). Treat staining as antibody-reactive FAM111B signal rather than an isoform-specific measurement until the immunogen and isoform coverage are documented (standard IHC interpretation). UniProt lists no signal peptide, transmembrane segment or glycosylation site, but those annotations do not establish whether fixation or retrieval preserves this antibody’s epitope (UniProt Q6SJ93). If an isoform-specific conclusion matters, verify the epitope against both sequences and compare independently validated reagents on adjacent sections with the same EDTA pH 8.0 retrieval (UniProt Q6SJ93; datasheet A14246-2; standard IHC practice).
How should I compare FAM111B IHC with multiplex IF?
Use IF as a separate assay comparison: HPA reports mainly nucleoplasmic FAM111B with additional cytosolic signal in ICC/IF, while its tissue IHC profile is mainly cytoplasmic (HPA subcellular; HPA tissue IHC). Multiplex with a marker that identifies the expected cell population in the specimen, and compare matched cell populations rather than whole-section brightness (standard IF practice). Select spectrally separated fluorophores after checking tissue autofluorescence and single-stain controls, especially when assigning weak cytosolic signal (standard IF practice). For an intracellular epitope, optimise permeabilisation after fixation; FAM111B has no annotated transmembrane segment or signal peptide, but this antibody’s precise epitope is unreported (UniProt Q6SJ93; datasheet A14246-2; standard IF practice).
What should I change when FAM111B DAB staining is diffuse?
Run a no-primary section through the same secondary and DAB steps to identify detection-related colour, and inspect tissue edges and damaged areas separately (standard IHC practice). The reported workflow used 10% goat serum, 2 µg/mL rabbit primary overnight at 4°C, and peroxidase-conjugated secondary for 30 minutes at 37°C (datasheet A14246-2). If background persists, optimise peroxidase blocking, washing and DAB development on matched sections; these are general chromogenic IHC controls, not demonstrated FAM111B-specific requirements (standard IHC practice). Interpret diffuse colour cautiously because HPA rates its tissue IHC reliability uncertain and reports presumed off-target binding (HPA tissue IHC).
How should I quantify FAM111B staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the scored cell population and compartment before analysis, since tissue IHC reports mainly cytoplasmic staining while ICC/IF reports mainly nucleoplasmic localisation (HPA tissue IHC; HPA subcellular). For cell-based comparisons, report percent positive cells and an H-score derived from the fraction of cells at each intensity; for spatial questions, report positive-cell density per mm² of viable analysed tissue (standard IHC practice). Normalise counts to the number of eligible cells or measured viable area, and keep retrieval, section thickness, imaging and DAB development consistent across samples (standard IHC practice). Record nuclear and cytoplasmic scores separately and exclude necrotic or folded regions under preset criteria (standard IHC practice).
How can I distinguish genuine FAM111B staining from artefact?
Prioritise reproducible cell-associated staining over colour confined to edges, folds or necrotic areas, and check a no-primary section for endogenous-enzyme or detection background (standard IHC practice). Medium staining in appendix lymphoid tissue and several glandular-cell populations, alongside absent staining in the listed adipocytes, offers comparison material but is not a specificity standard (HPA tissue IHC). Check compartment as well as cell type: tissue IHC is mainly cytoplasmic, whereas ICC/IF places signal mainly in the nucleoplasm and additionally in the cytosol (HPA tissue IHC; HPA subcellular). HPA calls tissue IHC reliability uncertain because staining and RNA show low consistency and presumed off-target binding was observed, so confirm consequential findings independently (HPA tissue IHC; standard IHC practice).
Boster reagents
Best FAM111B / Serine protease FAM111B IHC Antibodies
The catalog includes one human-reactive anti-FAM111B antibody with real IHC data from paraffin-embedded thyroid and bladder cancer tissue (A14246-2 image captions); no IF data are supplied (catalog).
Real IHC data
Anti-FAM111B Antibody ®
Cat # A14246-2
A14246-2 is listed for human IHC (catalog: applications and reactivity). Its images show staining in paraffin-embedded human thyroid and bladder cancer tissue (A14246-2 image captions); the fixative is unreported (A14246-2 image captions).
Which to pick: Choose A14246-2 for human paraffin-section IHC; its caption documents EDTA retrieval at pH 8.0 and primary antibody at 2 μg/ml (A14246-2 image caption). No listed SKU has IF/ICC validation or nonhuman reactivity (catalog: applications and reactivity), so there is no supported pick here for IF/ICC or cross-species work. The catalog does not specify a clone, and the IHC caption does not report the fixative (catalog: clone; A14246-2 image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q6SJ93 (F111B_HUMAN, Serine protease FAM111B).
- Human Protein Atlas. FAM111B tissue IHC expression (reliability: Uncertain).
- Human Protein Atlas. FAM111B subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to the cytosol..
- Human Protein Atlas. FAM111B antibody validation summary (1 antibodies).
- FAM111B enhances proliferation of KRAS-driven lung adenocarcinoma by degrading p16. Cancer science 2020 — PMC7385341.
- FAM111B Acts as an Oncogene in Bladder Cancer. Cancers 2023 — PMC10648174.
- FAM111B, a direct target of p53, promotes the malignant process of lung adenocarcinoma. OncoTargets and therapy 2019 — PMC6489872.
- Spatiotemporal microenvironment landscape and malignant epithelial pattern transition in breast ductal carcinoma progression. Journal of translational medicine 2025 — PMC12462311.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
- PubMed PMID:22814378 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FAM111B (Serine protease FAM111B). Expected localisation Mainly cytoplasmic in several tissues (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A14246-2). Validated IHC antibody: A14246-2 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Appendix (Lymphoid tissue); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded follicles of human thyroid cancer tissue; fixative not specified (datasheet A14246-2); 2. Fixation: Image fixative and duration unreported (datasheet A14246-2); 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 A14246-2); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A14246-2); 8. Primary antibody: Rabbit anti-FAM111B, 2-5 μg/ml (datasheet A14246-2); 9. Primary incubation: Overnight at 4 °C (datasheet A14246-2). Watch for: Fixation: Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific); Caveat: Possible off-target staining; low RNA concordance (HPA tissue IHC); Isoform / epitope: 2 isoforms; verify antibody epitope coverage (UniProt); Regulation: Tissue-enhanced RNA in lymphoid tissue (HPA tissue RNA). Evidence: UniProt Q6SJ93, HPA tissue IHC · Uncertain, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to the…, Datasheet A14246-2, PMC7385341, PMC10648174. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FAM111B/immunohistochemistry-ihc-guide.