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AFF4 / AF4/FMR2 family member 4 · IHC design guide
Design Immunohistochemistry for AFF4
Plan AFF4 paraffin IHC around an expected nuclear tissue pattern (HPA tissue IHC). The IHC-validated antibody has a recommended dilution of 2–5 μg/mL (datasheet A03824); interpret staining with the reported low consistency between antibody staining and RNA expression in mind (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
AFF4 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 staining in tissue (HPA tissue IHC) | |
| Staining pattern | Nuclear staining across many tissue cell types (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A03824) | |
| Positive control | Caudate+4 more · see all | |
| Negative control | Ovary |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | Staining and RNA expression show low consistency (HPA tissue IHC) | |
| Regulation | High in glia and early spermatids (HPA tissue IHC) | |
| Isoform / epitope | Three isoforms; epitope coverage is unreported (UniProt) |
Section 1
Recommended AFF4 IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet: A03824) is accompanied by a published protocol for a human HNSCC tissue array (PMC6031063).
| Sample | Paraffin-embedded human placenta tissue; fixative not specified (datasheet A03824) |
| Fixation | Image fixative and duration unreported (datasheet A03824); 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 A03824); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A03824) |
| Primary antibody | Rabbit anti-AFF4, 2-5μg/ml (datasheet A03824) |
| Primary incubation | Overnight at 4 °C (datasheet A03824) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A03824) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | AFF4-positive staining in glial cells of caudate (HPA tissue IHC: High). HPA tissue profile: Ubiquitous nuclear expression. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA retrieval at pH 8.0 (datasheet: A03824); the HNSCC paper reports antigen retrieval without specifying its conditions (PMC6031063).
Section 2
What Is the Expected AFF4 Staining Pattern?
AFF4 is a nuclear protein associated with transcriptionally active chromatin and has no transmembrane segment (UniProt Q9UHB7). Expect nuclear staining across many cell types, with high staining reported in glial cells in several brain regions and round or early spermatids in testis (HPA: tissue IHC). HPA describes ubiquitous nuclear expression, but its tissue IHC reliability is Approved with low consistency between antibody staining and RNA expression (HPA: tissue IHC).
| Distinct nuclear signal in the expected cells, with less staining outside nuclei. | This fits AFF4 localisation to the nucleus and chromosome (UniProt Q9UHB7) and HPA's ubiquitous nuclear IHC profile (HPA: tissue IHC). High signal in glial cells of the caudate, cerebral cortex or hippocampus, or in round or early spermatids, is consistent with the reported cell-level observations (HPA: High in those cells). Compare cells within the same section; intensity alone cannot establish antibody specificity. |
| Strong membrane or predominantly cytoplasmic staining, with little nuclear signal. | That compartment pattern conflicts with AFF4's nuclear localisation and lack of a transmembrane segment (UniProt Q9UHB7). Treat it as suspect staining and inspect the negative control and detection chemistry. A weak cytoplasmic haze accompanying convincing nuclear signal has a different interpretation from a dominant nonnuclear pattern; assess the nuclear result before calling the section positive. |
| Signal concentrates in a cell type reported as unstained, such as ovarian stroma, while expected nuclei are weak. | HPA reports ovarian stromal cells as not detected (HPA: tissue IHC), so a strong isolated result there deserves scrutiny for cross-reactivity or endogenous detection activity. This is a comparison, not an absolute biological exclusion: HPA also reports low consistency between staining and RNA data (HPA: reliability description). Check morphology and controls before assigning the signal to AFF4. |
| Diffuse colour covers tissue, empty spaces or many cells without clear nuclear boundaries. | The pattern gives poor evidence of AFF4 because its expected localisation is nuclear (UniProt Q9UHB7; HPA: tissue IHC). General IHC practice: diffuse background can arise from nonspecific binding or detection chemistry. Compare a matched negative control, inspect wash and blocking steps, and score only signal that can be assigned to intact cells and their nuclei. |
| No nuclear signal appears in a section chosen for its reported high staining. | A caudate section with glial cells or testis with round or early spermatids offers an HPA-reported high-staining comparison (HPA: tissue IHC). Absence there raises a workflow or specimen question, but does not by itself prove AFF4 is absent: HPA rates tissue IHC Approved while reporting low staining–RNA consistency (HPA: reliability description). Confirm the relevant cell population is present. |
💡Expected AFF4 appearanceCall a result positive when nuclei stain clearly in the relevant cells, potentially strongly in brain glial cells or round or early spermatids (HPA: High in those cells); dominant membrane or diffuse extranuclear colour is suspect (UniProt Q9UHB7 nuclear localisation and topology).
| Tissue and cell context | HPA reports high staining in selected brain glial cells and round or early spermatids, medium staining in adrenal glandular cells and bone marrow hematopoietic cells, and no detection in ovarian stroma (HPA: tissue IHC). Choose comparison areas by cell type, not tissue name alone; HPA's low staining–RNA consistency limits how strongly any single intensity should be interpreted (HPA: reliability description). |
| Antibody validation | The tissue IHC profile is Approved, with an explicit low-consistency caveat (HPA: tissue IHC). HPA023690 is listed as IHC Approved, while HPA029634 and HPA076229 are listed as ICC Supported without IHC status (HPA: antibody validation). An ICC result from those entries does not independently validate a chromogenic paraffin-section result. |
| Isoforms and antigen identity | UniProt lists 3 AFF4 isoforms and a full-length chain spanning residues 1–1163, with no signal peptide or propeptide annotated (UniProt Q9UHB7). The supplied sources do not map the IHC antibody epitope to an isoform. If a section disagrees with the expected pattern, check the antibody's stated immunogen and application information before attributing it to isoform expression. |
| IF/ICC Q&A: what localisation is expected? | HPA reports mainly nucleoplasmic signal, with additional nucleolar fibrillar-center and nuclear-body localisation in ICC-IF (HPA: subcellular, supported). These finer structures can guide interpretation of an IF image, but chromogenic IHC need only show a credible nuclear pattern; the ICC-IF observations do not specify an IHC protocol or guarantee that subnuclear detail will resolve in paraffin sections. |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected high-staining cells are present, but their nuclei are blank. | The result conflicts with reported high staining in those cells (HPA: tissue IHC); the primary or detection workflow may have failed. | General IHC practice: verify the primary antibody's IHC-P instructions, the stated retrieval and dilution, and the detection controls. Recheck cell identity and section quality before recording a negative AFF4 call. |
| Only cytoplasm or cell borders stain. | Predominantly extranuclear staining conflicts with AFF4's nuclear location and lack of a transmembrane segment (UniProt Q9UHB7). | Review matched negative controls, antibody application information and cell boundaries. Score nuclear and extranuclear staining separately; avoid treating a bright border as a positive AFF4 nucleus. |
| Ovarian stromal cells stain strongly. | That differs from HPA's not-detected observation for ovarian stroma (HPA: tissue IHC), although HPA notes low staining–RNA consistency (HPA: reliability description). | Confirm stromal identity and examine a negative detection control for endogenous activity. Compare with an HPA-reported high-staining cell population before interpreting the isolated result. |
| Brown colour is spread across the section without cell-specific nuclear contrast. | Diffuse background obscures the nuclear pattern expected for AFF4 (UniProt Q9UHB7; HPA: tissue IHC). | General IHC practice: inspect blocking, washing, detection timing and a no-primary control. Reduce background through the validated workflow, then reassess whether identifiable nuclei retain signal. |
| Nuclear staining is present but weaker than expected in a reported high-staining tissue. | The sampled area may lack the relevant high-staining cells; HPA levels are cell-specific and its tissue IHC has low staining–RNA consistency (HPA: tissue IHC). | Compare like cell types across sections and record the distribution as well as intensity. Confirm the selected glial or spermatid population before changing the interpretation or technical conditions. |
| IF shows nuclear dots, but chromogenic IHC looks broadly nuclear. | ICC-IF reports additional nuclear-body and nucleolar fibrillar-center localisation alongside mainly nucleoplasmic AFF4 (HPA: subcellular, supported). | Interpret each assay at its available resolution. For this IHC section, judge nuclear staining against tissue and cell context (HPA: tissue IHC); use the separate IF/ICC guide for imaging-specific decisions. |
Experiment evidence
IHC & IF images showing AFF4 staining
A03824 · IHCIHC analysis of AFF4 using anti-AFF4 antibody (A03824). AFF4 was detected in a paraffin-embedded section of human placenta tissue. Heat medi
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000072364-AFF4/tissue/cerebral+cortex#imid_6082184
HPA · HippocampusHuman Protein Atlas IHC, Hippocampus. Source: https://www.proteinatlas.org/ENSG00000072364-AFF4/tissue/hippocampal+formation#imid_6082185
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000072364-AFF4/tissue/colon#imid_6082118
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000072364-AFF4/tissue/liver#imid_6082103
HPA · ICC-IF CACO-2Human Protein Atlas immunofluorescence, CACO-2, antibody HPA029634; green = AFF4, blue = nucleus, red = microtubules.
HPA · ICC-IF CACO-2Human Protein Atlas immunofluorescence, CACO-2, antibody HPA029634; green = AFF4, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for AFF4 IHC & IF
🧪Run caudate first; glial cells should show nuclear AFF4 staining (HPA: High in caudate glial cells; UniProt: nucleus). Use ovarian stroma as the negative tissue (HPA: Not detected in ovarian stroma cells); cells without nuclear signal on the caudate slide provide a local background reference, although HPA identifies no validated negative cell type within caudate (HPA: caudate glial cells High).
Positive control tissue: Caudate (Glial cells, HPA High)
Negative control tissue: Ovary (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show AFF4 in CACO-2, SiHa, U2OS, U-251MG, with annotated localisation: Nucleoplasm (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a concentration-matched rabbit IgG isotype control; AFF4 knockout material, if available, provides a biological specificity control (standard IHC practice; selected A03824 caption: rabbit primary). Quench endogenous peroxidase in the caudate section and distinguish tissue pigment from DAB signal (standard chromogenic IHC practice).
⚠️Feasibility: No AFF4-specific fixation window or fixation effect is reported, and the selected A03824 paraffin-section caption does not state a fixative (selected A03824 caption). That caption uses heat retrieval in EDTA at pH 8.0 for placenta, but does not establish retrieval dependence in caudate (selected A03824 caption); the supplied evidence does not establish whether frozen sections or IF would be easier. For brain IF, assess tissue autofluorescence against a no-primary control before interpreting nuclear signal (standard IF practice; HPA: caudate glial cells High).
HPA tissue IHC evidence for AFF4
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low consistency between antibody staining and RNA expression data.). 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 |
|---|---|---|---|---|
| Caudate | Glial cells | High | Protein (IHC) | HPA → |
| Cerebellum | Cells in molecular layer | High | Protein (IHC) | HPA → |
| Cerebral cortex | Glial cells | High | Protein (IHC) | HPA → |
| Hippocampus | Glial cells | High | Protein (IHC) | HPA → |
| Testis | Round or early spermatids | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Ovary | Ovarian stroma cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced AFF4 IHC Tips
Troubleshoot AFF4 staining in paraffin sections by checking nuclear signal, retrieval, controls and scoring; use IF as a complementary localisation check.
How should I adjust retrieval when AFF4 nuclear staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections stained with A03824 (datasheet A03824). The demonstrated tissue-IHC workflow used 2 μg/ml primary antibody overnight at 4°C, so match those conditions before attributing weak signal to retrieval (A03824 tissue-IHC caption). Compare shorter and longer heating within a controlled retrieval series, checking that nuclei remain intact and sections remain attached (standard IHC practice). If staining stays weak, test an alternative retrieval buffer only as a fallback, with matched positive tissue and no-primary controls (standard IHC practice). Score nuclear signal separately from diffuse background because AFF4 is nuclear and chromatin-associated (UniProt Q9UHB7 localisation).
Could fixation explain weak or uneven AFF4 staining?
The selected paraffin-section caption does not state a fixative, so AFF4-specific fixation sensitivity is unknown (A03824 tissue-IHC caption). For a controlled pilot, hold tissue thickness, processing and EDTA pH 8.0 retrieval constant while comparing documented fixation conditions (standard IHC practice; datasheet A03824). Record time before fixation and fixation duration for each sample, then compare nuclear intensity and tissue preservation on the same staining run (standard IHC practice). Uneven penetration can produce regional staining differences, but such a pattern alone does not establish an AFF4-specific fixation effect (standard IHC practice). Interpret any pilot result alongside matched controls and the expected nuclear distribution (UniProt Q9UHB7 localisation).
Should AFF4 staining appear in the cytoplasm or nucleus?
Assess AFF4 primarily in nuclei: it associates with transcriptionally active chromatin, and the tissue-IHC profile describes ubiquitous nuclear expression (UniProt Q9UHB7 localisation; HPA tissue IHC). The subcellular IF profile places AFF4 mainly in the nucleoplasm, with additional signal in nucleolar fibrillar centers and nuclear bodies (HPA subcellular). Compare DAB deposition with a nuclear counterstain and score discrete nuclear signal separately from cytoplasmic haze (standard IHC practice). AFF4 has no annotated transmembrane segment, so a crisp membrane-only pattern warrants investigation rather than immediate biological interpretation (UniProt Q9UHB7 topology). Check the same compartment in a positive control section before changing the retrieval or detection steps (standard IHC practice).
How can isoforms or epitope masking affect AFF4 IHC?
AFF4 has 3 listed isoforms, but the supplied A03824 caption does not identify its immunogen or establish isoform-specific staining (UniProt Q9UHB7 isoforms; A03824 tissue-IHC caption). Obtain the antibody epitope coordinates and compare them with the expressed isoform sequences before treating a negative section as absence of all AFF4 isoforms (standard antibody-validation practice). AFF4 also has annotated modified residues, including phosphorylation at serines 387–389; their effect on this antibody is unknown without epitope information (UniProt Q9UHB7 modified residues). If results disagree across antibodies, compare nuclear patterns in matched sections using independently mapped epitopes and the same retrieval conditions (standard IHC practice).
How should IF help verify an AFF4 IHC pattern?
Use IF as a localisation follow-up: AFF4 is mainly nucleoplasmic, with additional nuclear structures reported in subcellular imaging (HPA subcellular). Multiplex AFF4 with a marker for the expected cell type, such as a glial marker when examining the reported glial staining, and include a nuclear counterstain (HPA tissue IHC; standard IF practice). Choose well-separated fluorophores and consider a far-red channel if the section has strong autofluorescence; inspect single-stain and no-primary controls (standard IF practice). Because AFF4 is nuclear and has no transmembrane segment, use controlled permeabilisation that gives antibody access to the nucleus while preserving its boundaries (UniProt Q9UHB7 localisation and topology; standard IF practice).
What should I check when AFF4 DAB staining is diffuse?
First distinguish nuclear DAB from staining in stroma, section edges or damaged regions by reviewing the counterstain and morphology (UniProt Q9UHB7 localisation; standard IHC practice). The demonstrated protocol blocked with 10% goat serum, used 2 μg/ml primary overnight at 4°C, then used a peroxidase-conjugated secondary and DAB (A03824 tissue-IHC caption). Run no-primary and secondary-only controls to locate detection-related background, and apply an endogenous-peroxidase block as a general chromogenic IHC step (standard IHC practice). If background persists, titrate primary concentration and shorten detection development while retaining a positive control on the same run (standard IHC practice). Do not count diffuse cytoplasmic colour as nuclear AFF4 without corroboration (UniProt Q9UHB7 localisation).
How can I quantify AFF4 across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and viable tissue area before scoring, then count only nuclei with signal above a fixed control-based threshold (UniProt Q9UHB7 localisation; standard IHC practice). Report the percentage of positive nuclei and, when intensity matters, an H-score from 0–300 using percentages at 1+, 2+ and 3+ intensity (standard IHC practice). Normalise cell counts to the number of evaluable nuclei, or report positive-cell density per mm² of viable tissue if cellularity varies (standard IHC practice). Use matched processing and imaging settings, exclude folds and necrosis, and analyse cell types separately because reported AFF4 staining levels vary among cell populations (standard IHC practice; HPA tissue IHC).
How do I distinguish true AFF4 staining from artefact?
A credible result has reproducible nuclear staining in intact cells, consistent with AFF4 localisation and the reported ubiquitous nuclear tissue profile (UniProt Q9UHB7 localisation; HPA tissue IHC). Treat isolated membrane or diffuse cytoplasmic signal, edge-heavy colour and staining confined to necrotic areas as prompts to check morphology and controls (UniProt Q9UHB7 topology and localisation; standard IHC practice). Reported high staining in glial cells and absent staining in ovarian stroma can guide cell-specific comparisons, but should not serve as absolute controls (HPA tissue IHC). Check no-primary controls and peroxidase blocking for endogenous-enzyme colour, then interpret discordant staining cautiously because HPA rates antibody staining and RNA expression consistency as low (standard IHC practice; HPA tissue IHC).
Boster reagents
Best AFF4 / AF4/FMR2 family member 4 IHC Antibodies
A03824 has a human placenta paraffin-section IHC image (catalog image caption); its listed IHC reactivity covers human, mouse, and rat (catalog applications/reactivity). No IF image is supplied (catalog image list).
Real IHC data
Anti-AFF4 Antibody ®
Cat # A03824
A03824 is listed for IHC in human, mouse, and rat samples (catalog applications/reactivity). Its image shows chromogenic IHC in a human placenta paraffin section (catalog image caption).
Which to pick: Choose A03824 for paraffin-section tissue IHC: its own image documents EDTA pH 8.0 retrieval and DAB detection in human placenta (catalog image caption). A03824 has no listed IF/ICC validation or IF image, so this payload supports no IF/ICC pick (catalog applications/image list). A03824 lists mouse and rat IHC reactivity, but the supplied image demonstrates human tissue only; the fixative is unreported (catalog applications/reactivity; catalog image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q9UHB7 (AFF4_HUMAN, AF4/FMR2 family member 4).
- Human Protein Atlas. AFF4 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. AFF4 subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to the nucleoli fibrillar center and nuclear bodies..
- Human Protein Atlas. AFF4 antibody validation summary (3 antibodies).
- AFF4 Predicts the Prognosis of Colorectal Cancer Patients and Suppresses Colorectal Cancer Metastasis via Promoting CDH1 Expression. Frontiers in oncology 2022 — PMC8865618.
- Impact of disulfidptosis-associated clusters on breast cancer survival rates and guiding personalized treatment. Frontiers in endocrinology 2023 — PMC10728640.
- AFF4 promotes tumorigenesis and tumor-initiation capacity of head and neck squamous cell carcinoma cells by regulating SOX2. Carcinogenesis 2018 — PMC6031063.
- AFF4 promotes tumor progression and cisplatin resistance by modulating the PTEN/PI3K/AKT/mTOR axis to accelerate glycolysis in lung adenocarcinoma. Cell & bioscience 2025 — PMC12337439.
- PubMed PMID:10588740 — UniProt-cited evidence.
- PubMed PMID:12065898 — UniProt-cited evidence.
- PubMed PMID:15372022 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for AFF4 (AF4/FMR2 family member 4). Expected localisation Nuclear staining in tissue (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A03824). Validated IHC antibody: A03824 at 2-5μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Caudate (Glial cells); negative Ovary. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human placenta tissue; fixative not specified (datasheet A03824); 2. Fixation: Image fixative and duration unreported (datasheet A03824); 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 A03824); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A03824); 8. Primary antibody: Rabbit anti-AFF4, 2-5μg/ml (datasheet A03824); 9. Primary incubation: Overnight at 4 °C (datasheet A03824). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Staining and RNA expression show low consistency (HPA tissue IHC); Isoform / epitope: Three isoforms; epitope coverage is unreported (UniProt); Regulation: High in glia and early spermatids (HPA tissue IHC). Evidence: UniProt Q9UHB7, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to the…, Datasheet A03824, PMC6031063. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/AFF4/immunohistochemistry-ihc-guide.