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CDKN2A / Cyclin-dependent kinase inhibitor 2A · IHC design guide
Design Immunohistochemistry for CDKN2A
Plan CDKN2A IHC-P around mainly nuclear staining in tissue (HPA tissue IHC). A formaldehyde-fixed human colon example uses the catalog antibody at 10 μg/mL (datasheet A00016-1 IHC-P).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CDKN2A 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 nuclear tissue staining (HPA tissue IHC) | |
| Staining pattern | Mainly nuclear staining in most tissues (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6 HIER, heat-mediated (datasheet A00016-1) | |
| 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 | Formaldehyde-fixed sections shown (selected-SKU IHC image A00016-1); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A00016-1) | |
| Caveat | Splice/transcript discrepancies may complicate interpretation (HPA tissue IHC) | |
| Regulation | RNA enhanced: choroid plexus, pituitary (HPA RNA) | |
| Isoform / epitope | Six isoforms; antibody epitope coverage unspecified (UniProt) |
Section 1
Recommended CDKN2A IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol (datasheet A00016-1) with a published primary melanoma IHC protocol (PMC2948432).
| Sample | Formaldehyde-fixed, paraffin-embedded Human Colon tissue (datasheet A00016-1) |
| Fixation | Image formalin-fixed; duration unreported (datasheet A00016-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: Citrate pH 6 (datasheet A00016-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% serum (datasheet A00016-1) |
| Primary antibody | Rabbit anti-CDKN2A, 5 - 10 μg/mL (datasheet A00016-1) |
| 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 | CDKN2A-positive staining in glandular cells of appendix (HPA tissue IHC: High). HPA tissue profile: Mainly nuclear expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated citrate retrieval at pH 6 for the catalog antibody (datasheet A00016-1). The melanoma article does not state retrieval conditions (PMC2948432).
Section 2
What Is the Expected CDKN2A Staining Pattern?
CDKN2A staining is expected mainly in nuclei, with possible cytoplasmic signal (HPA tissue IHC: mainly nuclear; UniProt P42771: nucleus and cytoplasm). Glandular cells in appendix and colon and elongated or late spermatids in testis are high-staining reference populations (HPA tissue IHC: High). CDKN2A has no transmembrane segment or signal peptide, so a membrane-restricted pattern is unexpected (UniProt P42771 topology). HPA rates the tissue profile Enhanced, while noting medium staining–RNA consistency and a splice or transcript discrepancy (HPA tissue IHC).
| Strong nuclear staining in appendix or colon glandular cells, or testis late spermatids. | This fits the reported high-staining cell populations and mainly nuclear tissue pattern (HPA tissue IHC: High; mainly nuclear). Judge staining in the named cells, not by whole-section darkness; other cells in the section are not established positive controls by these data. |
| Membrane-restricted staining, or cytoplasmic staining with no convincing nuclear signal in a known-positive population. | Recheck specificity and localization: CDKN2A is reported in the nucleus and cytoplasm, with no transmembrane segment (UniProt P42771); HPA tissue staining is mainly nuclear (HPA tissue IHC). Cytoplasmic signal alone is not proof of artifact, but a membrane-only result conflicts with the supplied localization evidence. |
| Strong staining in a cell population reported as not detected, such as adipocytes or skeletal-muscle myocytes. | Treat this as a possible specificity or detection-system problem and verify with controls; HPA reports these named populations as Not detected (HPA tissue IHC). A discrepant stain cannot by itself establish cross-reactivity, because staining patterns can vary with the antibody and assay. |
| Broad, diffuse chromogen deposits obscure nuclei and tissue structure. | Interpretability is limited: a haze lacks the mainly nuclear, cell-specific pattern reported for tissue CDKN2A (HPA tissue IHC). Consider nonspecific binding or endogenous detection activity as general IHC possibilities; the supplied sources do not identify a CDKN2A-specific cause. |
| No staining in appendix or colon glandular cells included as a positive reference. | The result conflicts with HPA's High staining for those populations (HPA tissue IHC: appendix and colon glandular cells, High). Check tissue identity and assay controls before calling the specimen negative; HPA also notes medium staining–RNA consistency and a splice or transcript discrepancy (HPA tissue IHC). |
💡Expected CDKN2A appearanceCall a result convincing when identifiable appendix or colon glandular cells, or late spermatids, show strong predominantly nuclear staining (HPA tissue IHC: High; mainly nuclear); isolated membrane staining or indiscriminate staining of reported negative cells warrants review (UniProt P42771 topology; HPA tissue IHC: Not detected populations).
| Reference tissue and cell population | HPA reports High staining in appendix and colon glandular cells and elongated or late spermatids in testis; adipocytes and skeletal-muscle myocytes are Not detected (HPA tissue IHC). Select and score the stated cell population, since a tissue label alone does not define every cell's expected result. |
| Antibody and transcript context | The tissue profile is Enhanced but has medium agreement with RNA and a splice or transcript discrepancy (HPA tissue IHC). CAB000445 has Enhanced IHC validation; CAB000093 and CAB018232 are Approved for IHC (HPA antibodies). CDKN2A has six annotated isoforms, including ARF (UniProt P42771); an antibody's exact isoform coverage is not supplied. |
| Compartment and processing | UniProt reports nuclear and cytoplasmic localization, no signal peptide, no propeptide and no transmembrane segment (UniProt P42771). HPA tissue staining is mainly nuclear (HPA tissue IHC). These records support checking the compartment, but do not establish any CDKN2A-specific antigen-retrieval or fixation response. |
| IF/ICC Q: What localization can corroborate IHC? | A: Nucleoplasm is supported in HPA ICC-IF; cytosol and primary-cilium locations are uncertain (HPA subcellular). Use this as a localization cross-check only: the tissue IHC profile is mainly nuclear (HPA tissue IHC), and the supplied ICC-IF record does not define an IHC protocol. |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in a high-staining reference population. | The run may have failed, the selected cell population may be absent, or antibody coverage may differ across isoforms (general IHC practice; UniProt P42771: six isoforms). | Confirm appendix or colon glandular cells are present and review positive controls, antibody documentation and detection steps (HPA tissue IHC: High in those cells; general IHC practice). Do not infer a CDKN2A-specific fixation effect from this result. |
| Only membrane outlines stain. | The pattern is inconsistent with reported nucleus/cytoplasm localization and absence of a transmembrane segment (UniProt P42771 topology). | Compare with a known-positive nuclear reference and appropriate reagent controls; reassess antibody specificity and chromogen deposits (HPA tissue IHC: mainly nuclear; general IHC practice). |
| Reported negative cells stain strongly. | Nonspecific antibody binding or endogenous detection activity is possible (general IHC practice); HPA reports adipocytes and skeletal-muscle myocytes as Not detected (HPA tissue IHC). | Check no-primary and detection controls, then score the exact cell population rather than the entire tissue (general IHC practice; HPA tissue IHC: cell-level annotations). |
| Diffuse background masks cell boundaries. | Nonspecific binding, insufficient washing or endogenous detection activity can produce background in chromogenic IHC (general IHC practice). | Review blocking, washes and detection controls, then reassess whether nuclei remain distinguishable (general IHC practice; HPA tissue IHC: mainly nuclear pattern). |
| Cytoplasmic signal accompanies nuclear staining. | Cytoplasmic localization is recorded by UniProt, while HPA describes tissue staining as mainly nuclear (UniProt P42771; HPA tissue IHC). | Record nuclear and cytoplasmic staining separately; compare cell-specific distribution with the reference tissue before labeling the cytoplasmic component nonspecific (HPA tissue IHC: mainly nuclear; general IHC practice). |
| Brain staining conflicts with an expected negative result. | UniProt says CDKN2A is not detected in brain, whereas HPA reports Medium staining in caudate glial cells and cerebellar molecular-layer cells (UniProt P42771 tissue specificity; HPA tissue IHC). | Document the cell type and antibody used; interpret the discrepancy cautiously in light of HPA's medium staining–RNA consistency and splice or transcript warning (HPA tissue IHC). |
Experiment evidence
IHC & IF images showing CDKN2A staining
A00016-1 · IHCImmunohistochemistry Validation of CDKN2A in Human Colon Tissue Immunohistochemical analysis of paraffin-embedded Human Colon Tissue using a
A00016-1 · IHCImmunohistochemistry Validation of CDKN2A in Rat Colon Tissue Immunohistochemical analysis of paraffin-embedded Rat Colon Tissue using anti-
A00016-1 · IFImmunofluorescence Validation of CDKN2A In HeLa Cells Immunofluorescent analysis of methanol-fixed HeLa cells labeling CDKN2A with A00016-1
A00016-3 · IHCImmunohistochemistry analysis of paraffin-embedded rat liver tissue (A) , human brain tumor (B) , breast cancer (C) , esophageal epithelium
M00016 · IHCImmunohistochemical analysis of paraffin-embedded human gastric, using p16 INK Antibody.
M00016 · IFImmunofluorescent analysis using the Antibody at 1:150 dilution.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000147889-CDKN2A/tissue/cerebral+cortex#imid_370718
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000147889-CDKN2A/tissue/colon#imid_370652
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000147889-CDKN2A/tissue/liver#imid_370653
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000147889-CDKN2A/tissue/kidney#imid_370646
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB000445; green = CDKN2A, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB000445; green = CDKN2A, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CDKN2A IHC & IF
🧪Run colon first: glandular cells should stain (HPA: High in colon glandular cells). Use skeletal muscle as the negative tissue (HPA: Not detected in skeletal-muscle myocytes); cells without specific staining on the colon slide should show only counterstain and background-level chromogen, without assigning an unlisted colon cell type as definitively negative.
Positive control tissue: Appendix (Glandular cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CDKN2A in A-431, U-251MG, U2OS, HEK293, SiHa, ASC52telo, RPTEC/TERT1, hTERT-RPE1 (serum starved), with annotated localisation: Nucleoplasm (supported) (HPA subcellular).
Technical controls: Include no-primary (secondary-only), a concentration-matched isotype control matched to the primary antibody’s host species and clonality where possible, and a CDKN2A knockout biological control (standard IHC practice). Check endogenous peroxidase activity before HRP detection in colon sections (selected-SKU caption: HRP secondary; standard IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported in the supplied evidence; the selected-SKU fixative field is unreported, although its caption describes formaldehyde fixation (selected-SKU caption and fixative field). Start with heat-mediated citrate retrieval at pH 6, as used in the paraffin-section colon example; a strict retrieval dependency is unreported (selected-SKU caption). Frozen-section or IF/ICC processing is not established as easier by the supplied evidence; assess nonspecific glandular background against controls when scoring colon staining (selected-SKU caption: colon tissue; standard IHC practice).
HPA tissue IHC evidence for CDKN2A
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. Caution, Splice and/or transcript discrepancy exists.). 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 | High | Protein (IHC) | HPA → |
| Colon | Glandular cells | High | Protein (IHC) | HPA → |
| Testis | Elongated or late spermatids | High | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | Medium | Protein (IHC) | HPA → |
| Breast | 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 → |
| Fallopian tube | Ciliated cells (cell body) | Not detected | Protein (IHC) | HPA → |
| Skeletal muscle | Myocytes | Not detected | Protein (IHC) | HPA → |
| Soft tissue | Fibroblasts | Not detected | Protein (IHC) | HPA → |
| Vagina | Squamous epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced CDKN2A IHC Tips
Troubleshoot CDKN2A staining in paraffin section IHC by checking retrieval, compartment, cell type, antibody epitope, and controls before interpreting chromogenic signal.
What retrieval should I try when CDKN2A staining is weak?
Start with heat-mediated retrieval in citrate buffer at pH 6 (datasheet A00016-1). The selected antibody's paraffin-section image used that retrieval and 10 µg/ml primary antibody, so use those conditions as a documented starting point when assessing weak staining (datasheet A00016-1). Check that sections stayed covered by buffer during heating and cooled consistently before staining (standard IHC practice). Compare the weak section with colon glandular cells, where protein staining is reported as high, while keeping detection and exposure conditions matched (HPA: High in colon glandular cells; standard IHC practice). If signal remains weak, test an alternative retrieval condition on adjacent sections and judge improvement against background and tissue morphology (standard IHC practice).
Could fixation explain inconsistent CDKN2A staining across paraffin blocks?
Target-specific fixation sensitivity for CDKN2A is unknown from the supplied evidence; do not assign a weak block to overfixation without a controlled comparison. Document each block's fixative, fixation duration, tissue thickness, and processing history before comparing staining intensity (standard IHC practice). Stain sections from differently processed blocks in the same run with citrate retrieval at pH 6 and a shared detection workflow (datasheet A00016-1; standard IHC practice). Include a positive tissue section in every run; colon glandular cells have reported high staining (HPA: High in colon glandular cells). If only one block fails, repeat with an adjacent section and examine preservation and background before changing antibody concentration (standard IHC practice).
How should I assess nuclear versus cytoplasmic CDKN2A signal?
Score nuclear and cytoplasmic staining separately because CDKN2A is annotated in both compartments, while tissue IHC is mainly nuclear (UniProt P42771: nucleus and cytoplasm; HPA: mainly nuclear expression). Use the hematoxylin counterstain to locate nuclei and examine whether chromogen follows intact cell boundaries rather than folds or debris (datasheet A00016-1; standard IHC practice). Predominantly nuclear staining in colon glandular cells is a useful comparison pattern, given their reported high protein staining (HPA: High in colon glandular cells; HPA: mainly nuclear expression). Cytoplasmic staining alone deserves closer scrutiny, but should not be dismissed solely by compartment because cytoplasmic localisation is annotated (UniProt P42771: cytoplasm). Record the fraction of cells stained in each compartment under the same scoring rules (standard IHC practice).
Can this antibody distinguish p16 from other CDKN2A products?
Do not assume isoform specificity until the catalog antibody's immunogen or mapped epitope is checked against the 6 listed CDKN2A isoforms (UniProt P42771: isoforms 1, 2, 3, ARF, 5, and smARF). CDKN2A also has annotated phosphorylation sites, including Ser7, Ser8, Ser140, and Ser152; epitope overlap or modification sensitivity cannot be inferred without antibody mapping (UniProt P42771: modified residues). Compare the stated epitope with isoform sequences before interpreting chromogenic staining as specifically p16-INK4a (UniProt P42771: p16-INK4a and alternative isoforms; standard antibody validation practice). If the epitope is undisclosed, report staining as antibody-detected CDKN2A and seek an independent antibody or orthogonal assay for isoform claims (standard IHC practice). Apply the same interpretation rule to positive and negative sections (standard IHC practice).
How can IF help resolve ambiguous CDKN2A IHC localisation?
Use the separate IF/ICC guide for assay setup; here, multiplex imaging can help assign a signal to the expected cell population and compartment. Pair CDKN2A with a validated marker of the cell type being examined, and include a nuclear stain because HPA reports mainly nuclear tissue expression and supported nucleoplasmic localisation (HPA: tissue IHC profile; HPA: nucleoplasm supported). Choose a fluorophore channel after checking tissue autofluorescence and single-stain controls, especially when chromogenic IHC background obscures cell boundaries (standard IF practice). For intracellular epitopes, evaluate permeabilisation against the mapped epitope and preservation of nuclear structure; CDKN2A has no annotated transmembrane segment (UniProt P42771: topology; standard IF practice). Treat cytosolic or ciliary IF signal cautiously because those HPA locations are uncertain (HPA: additional subcellular locations uncertain).
What should I check when CDKN2A chromogen covers the whole section?
Compare a no-primary control with the stained section to locate background from the secondary detection system or endogenous enzyme activity (standard IHC practice). The selected tissue image used 10% serum blocking for 1 hour at room temperature, then an HRP secondary at 1:250 (datasheet A00016-1). Confirm peroxidase blocking and inspect whether chromogen accumulates at section edges, folds, or damaged areas (standard chromogenic IHC practice). Excessive diffuse cytoplasmic colour should be assessed against the mainly nuclear tissue pattern, although cytoplasmic CDKN2A localisation is annotated (HPA: mainly nuclear expression; UniProt P42771: cytoplasm). Keep development conditions identical between test and control sections when judging whether a blocking or detection change helped (standard IHC practice).
How should I quantify CDKN2A staining across samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the scored cell population and compartment before comparing sections; HPA reports mainly nuclear tissue staining and high signal in colon glandular cells (HPA: tissue IHC profile; HPA: High in colon glandular cells). For nuclear staining, record percent positive cells and intensity grades 0–3, then calculate an H-score using the same thresholds across samples (standard IHC scoring practice). If cell abundance differs, report positive cells per mm² of viable, annotated tissue alongside the fraction of eligible cells that are positive (standard image analysis practice). Exclude folds, necrosis, and cut edges using rules fixed before scoring (standard IHC practice). Normalise to the relevant cell population and usable tissue area, and compare batches using the same positive control section (standard IHC practice).
How do I distinguish convincing CDKN2A positivity from artefact?
Look first for staining in intact cells and assess nuclear signal separately, because tissue IHC is mainly nuclear while CDKN2A can also localise to cytoplasm (HPA: mainly nuclear expression; UniProt P42771: nucleus and cytoplasm). Colon glandular cells provide a reported high-staining comparison, whereas adipocytes and skeletal-muscle myocytes are reported as undetected (HPA: tissue IHC profile). A signal limited to cut edges, folds, necrotic regions, or the no-primary control points to a staining artefact or detection background (standard IHC practice). Check endogenous peroxidase blocking when diffuse DAB persists, and compare cells within well-preserved areas (standard chromogenic IHC practice). Because HPA notes a splice or transcript discrepancy, avoid treating staining alone as proof of a particular CDKN2A isoform (HPA: reliability description; UniProt P42771: isoforms).
Boster reagents
Best CDKN2A / Cyclin-dependent kinase inhibitor 2A IHC Antibodies
IHC figures cover human and rat colon, rat liver, mouse brain, and human gastric tissue (catalog IHC captions); IF figures cover human cells and human or rat colon tissue (A00016-1 IF captions).
Real IHC data
Anti-CDKN2A/CDKN2A/p16INK4a Antibody
Cat # A00016-1
Real IHC data
Anti-p16 CDKN2A Monoclonal Antibody
Cat # A00016-3
Real IHC data
Anti-p16 INK Monoclonal Antibody
Cat # M00016
A00016-1 shows paraffin-section IHC in human and rat colon and IF in HeLa, A431, and human and rat colon (A00016-1 IHC/IF captions); A00016-3 shows paraffin-section IHC in rat liver, human brain tumor, breast cancer, esophageal epithelium, mouse brain, and stomach tissue (A00016-3 IHC caption). M00016 shows paraffin-section IHC in human gastric tissue (M00016 IHC caption) and lists human IF/ICC applications, although its IF captions do not identify the specimens (M00016 applications, reactivity, IF captions).
Which to pick: For tissue IHC, choose A00016-1: its human and rat colon paraffin-section examples report formaldehyde fixation and citrate retrieval at pH 6 (A00016-1 IHC captions). For human IF/ICC, M00016 is a rabbit monoclonal listing both applications; its IHC example uses paraffin-embedded human gastric tissue, with the fixative unreported (M00016 catalog clone, applications, reactivity, IHC caption). For cross-species paraffin-section IHC, A00016-3 is a mouse monoclonal with rat liver, mouse brain, and human tissue examples; its caption does not report the fixative (A00016-3 catalog clone, IHC caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P42771 (CDN2A_HUMAN, Cyclin-dependent kinase inhibitor 2A).
- Human Protein Atlas. CDKN2A tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. CDKN2A subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to the cytosol, primary cilium, primary cilium tip and primary cilium transition zone..
- Human Protein Atlas. CDKN2A antibody validation summary (4 antibodies).
- p16 Immunohistochemistry as a Screening Tool for Homozygous CDKN2A Deletions in CNS Tumors. The American journal of surgical pathology 2024 — PMC10723769.
- Deletion at chromosome arm 9p in relation to BRAF/NRAS mutations and prognostic significance for primary melanoma. Genes, chromosomes & cancer 2010 — PMC2948432.
- p16 Immunohistochemical Expression as a Surrogate Assessment of CDKN2A Alteration in Gliomas Leading to Prognostic Significances. Cancers 2023 — PMC10000516.
- Deletions of CDKN2A and MTAP Detected by Copy-Number Variation Array Are Associated with Loss of p16 and MTAP Protein in Pleural Mesothelioma. Cancers 2023 — PMC10605896.
- PubMed PMID:8259215 — UniProt-cited evidence.
- PubMed PMID:10445844 — UniProt-cited evidence.
- PubMed PMID:12228235 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CDKN2A (Cyclin-dependent kinase inhibitor 2A). Expected localisation Mainly nuclear tissue staining (HPA tissue IHC). Antigen retrieval: Citrate pH 6 HIER, heat-mediated (datasheet A00016-1). Validated IHC antibody: A00016-1 at 5 - 10 μg/mL (the product's own IHC validation image is shown). Controls (HPA): positive Appendix (Glandular cells); negative Adipose tissue. IHC-P workflow on paraffin sections. Protocol steps: 1. Sample: Formaldehyde-fixed, paraffin-embedded Human Colon tissue (datasheet A00016-1); 2. Fixation: Image formalin-fixed; duration unreported (datasheet A00016-1); 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 retrieval: Citrate pH 6 (datasheet A00016-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% serum (datasheet A00016-1); 8. Primary antibody: Rabbit anti-CDKN2A, 5 - 10 μg/mL (datasheet A00016-1); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Formaldehyde-fixed sections shown (selected-SKU IHC image A00016-1); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A00016-1); Caveat: Splice/transcript discrepancies may complicate interpretation (HPA tissue IHC); Isoform / epitope: Six isoforms; antibody epitope coverage unspecified (UniProt); Regulation: RNA enhanced: choroid plexus, pituitary (HPA RNA). Evidence: UniProt P42771, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to the…, Datasheet A00016-1, PMC2948432. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CDKN2A/immunohistochemistry-ihc-guide.