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KRT6A / Keratin, type II cytoskeletal 6A · IHC design guide
Design Immunohistochemistry for KRT6A
This KRT6A IHC-P guide covers the cytoplasmic staining expected in squamous and respiratory epithelia (HPA tissue IHC). Use cervical squamous epithelium as a positive control (HPA tissue IHC), and account for staining that may reflect proteins from more than one gene (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
KRT6A 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 | Cytoplasm in squamous and respiratory epithelia (HPA tissue IHC) | |
| Staining pattern | Squamous and respiratory epithelial cells show cytoplasmic staining (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet M30943-1) | |
| Positive control | Cervix+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 sections (standard IHC practice; not target-specific) | |
| Caveat | Staining may reflect proteins from more than one gene (HPA tissue IHC) | |
| Regulation | Wound-edge induction (by similarity) (UniProt) | |
| Isoform / epitope | No annotated isoforms; chain starts at residue 2 (UniProt) |
Section 1
Recommended KRT6A IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol (datasheet M30943-1) with the four published KRT6A IHC protocols listed below (cited PMCs).
| Sample | Paraffin-embedded human cervical cancer tissue; fixative not specified (datasheet M30943-1) |
| Fixation | Image fixative and duration unreported (datasheet M30943-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet M30943-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet M30943-1) |
| Primary antibody | Rabbit monoclonal (clone GAO-11) anti-KRT6A, 1:50-1:200 (datasheet M30943-1) |
| Primary incubation | Overnight at 4 °C (datasheet M30943-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet M30943-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | KRT6A-positive staining in squamous epithelial cells of cervix (HPA tissue IHC: High). HPA tissue profile: Distinct cytoplasmic expression in squamous and respiratory epithelia. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval for the catalog antibody (datasheet M30943-1). The first three published protocols use citrate pH 6.0 (PMC13469621; PMC13382563; PMC13359832).
Section 2
What Is the Expected KRT6A Staining Pattern?
KRT6A is a cytoplasmic keratin with no transmembrane segment (UniProt P02538). In IHC, expect staining in squamous epithelial cells of cervix, esophagus, oral mucosa, tonsil and vagina, and respiratory epithelial cells of nasopharynx (HPA tissue IHC: High). HPA rates its tissue pattern Supported, while cautioning that the antibodies may detect proteins from more than one gene (HPA tissue IHC: reliability).
| Distinct cytoplasmic staining in squamous epithelium, with adjacent cell types comparatively unstained. | This matches the reported distribution in cervix, esophagus, oral mucosa, tonsil and vagina (HPA tissue IHC: High in squamous epithelial cells). Assess staining by cell type and compartment: KRT6A is cytoplasmic (UniProt P02538), and HPA describes a distinct epithelial pattern (HPA tissue IHC: profile). |
| Predominantly nuclear staining, with little epithelial cytoplasmic staining. | Nuclear dominance conflicts with the recorded cytoplasmic location (UniProt P02538) and intermediate filament localization seen by ICC-IF (HPA subcellular: intermediate filaments). Treat it as a suspect pattern; review controls, detection background and scoring before calling the section KRT6A positive (general IHC practice). |
| Strong staining in cells outside the expected epithelial population. | Staining in, for example, adipocytes or hematopoietic cells conflicts with HPA observations for those cells (HPA tissue IHC: Not detected in adipocytes and hematopoietic cells). Cross-reactivity or endogenous detection activity is possible (general IHC practice); the HPA multi-gene antibody caution makes target identity especially important (HPA tissue IHC: reliability). |
| Diffuse color across epithelium, stroma and blank areas, without clear cell boundaries. | A widespread haze does not reproduce HPA's distinct epithelial cytoplasmic pattern (HPA tissue IHC: profile). Inspect no-primary and detection controls, washes and blocking for nonspecific or endogenous signal (general IHC practice). Do not score intensity until the epithelial signal can be distinguished from background (general IHC practice). |
| No epithelial signal in a section chosen as a positive control. | First confirm that the sampled region contains the relevant cells: HPA reports High staining in oral mucosa squamous cells and nasopharyngeal respiratory cells (HPA tissue IHC). Then check the run controls and antibody detection; absence of signal alone cannot establish biological absence (general IHC practice). |
💡Expected KRT6A appearanceCall a convincing positive result when epithelial cells show distinct cytoplasmic staining, often High in the listed squamous or nasopharyngeal sites (HPA tissue IHC); isolated nuclear color or widespread staining of unrelated cells is suspect (UniProt P02538; HPA tissue IHC: profile; general IHC practice).
| Compartment and structure | KRT6A is cytoplasmic and forms keratin intermediate filament networks with type I keratins (UniProt P02538). HPA ICC-IF places the signal on intermediate filaments (HPA subcellular). In chromogenic IHC, evaluate cytoplasmic distribution; a filament-like pattern may be easier to resolve by IF microscopy (general microscopy practice). |
| Tissue and cell selection | HPA reports High staining in several squamous epithelia and nasopharyngeal respiratory cells, but Medium staining in bronchial respiratory cells (HPA tissue IHC). Choose a documented High site when assessing assay performance; compare the correct epithelial cells rather than assigning one intensity to the entire section (general IHC practice). |
| Antibody specificity | Two listed antibodies, HPA045697 and HPA061168, have IHC Supported status (HPA antibodies). HPA also cautions that its staining may reflect proteins from more than one gene (HPA tissue IHC: reliability). Agreement with the expected pattern supports interpretation, but these data alone do not prove that every stained cell contains KRT6A specifically. |
| Biological state | KRT6A is rapidly induced in wound-edge keratinocytes, according to a similarity-based UniProt annotation (UniProt P02538: function). A sampled repair region may therefore differ from resting epithelium; record whether the section contains an epithelial wound edge before comparing regions (UniProt P02538: function; general IHC practice). |
| IF/ICC: what should I expect? | Expect cytoplasmic intermediate filament localization (HPA subcellular: intermediate filaments; UniProt P02538: cytoplasm). HPA lists ICC-IF images and marks both listed antibodies ICC Approved (HPA subcellular; HPA antibodies). Use the separate IF/ICC guide for its workflow; these records supply no IF dilution or permeabilisation setting. |
| Fixation and retrieval evidence | Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation. |
| Situation | Likely cause | Next action |
|---|---|---|
| A known-positive epithelial region is blank. | The sampled area may lack the documented positive cells, or staining or detection may have failed (HPA tissue IHC: positive cell types; general IHC practice). | Confirm epithelial identity on the section, then inspect the positive run control and the chosen antibody's IHC-P instructions for retrieval, dilution and detection (general IHC practice). |
| Only nuclei appear positive. | Nuclear dominance conflicts with cytoplasmic KRT6A and HPA intermediate filament localization (UniProt P02538; HPA subcellular). | Check the no-primary control, counterstain and detection background; require interpretable epithelial cytoplasmic signal before scoring a positive result (general IHC practice). |
| Unrelated cells stain as strongly as the epithelium. | Cross-reactivity or endogenous detection activity may contribute (general IHC practice); HPA cautions that antibodies may target more than one gene (HPA tissue IHC: reliability). | Compare the suspect cells with HPA cell-level observations and review no-primary and detection controls. Report unresolved staining as uncertain rather than assigning it specifically to KRT6A (HPA tissue IHC; general IHC practice). |
| The whole section has diffuse chromogenic background. | Nonspecific binding, insufficient washing or endogenous detection activity can obscure a distinct epithelial pattern (general IHC practice; HPA tissue IHC: profile). | Review blocking, washes and detection controls under the assay's standard IHC workflow; reassess only where cytoplasmic epithelial signal separates clearly from background (general IHC practice). |
| Bronchial staining looks weaker than a squamous positive control. | HPA reports Medium staining in bronchial respiratory cells and High staining in several squamous epithelial populations (HPA tissue IHC). | Score bronchial respiratory cells against their documented level and local controls. Do not use equal intensity across the two tissues as the criterion for a successful run (HPA tissue IHC; general IHC practice). |
| A section differs from the HPA reference pattern. | Differences in sampled epithelial cells or a repair region can affect interpretation (HPA tissue IHC: cell-level pattern; UniProt P02538: wound-edge induction by similarity). | Document the tissue region and cell type, check run controls, and compare matching epithelial populations. If staining remains discordant, report the limitation and the HPA multi-gene antibody caution (general IHC practice; HPA tissue IHC: reliability). |
Experiment evidence
IHC & IF images showing KRT6A staining
M30943-1 · IHCIHC analysis of Cytokeratin 6 using anti-Cytokeratin 6 antibody (M30943-1). Cytokeratin 6 was detected in a paraffin-embedded section of hum
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000205420-KRT6A/tissue/cerebral+cortex#imid_14539456
HPA · EsophagusHuman Protein Atlas IHC, Esophagus. Source: https://www.proteinatlas.org/ENSG00000205420-KRT6A/tissue/esophagus#imid_14539428
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000205420-KRT6A/tissue/colon#imid_14539390
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000205420-KRT6A/tissue/liver#imid_14539391
HPA · ICC-IF HaCaTHuman Protein Atlas immunofluorescence, HaCaT, antibody HPA045697; green = KRT6A, blue = nucleus, red = microtubules.
HPA · ICC-IF HaCaTHuman Protein Atlas immunofluorescence, HaCaT, antibody HPA045697; green = KRT6A, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for KRT6A IHC & IF
🧪Run cervix first: squamous epithelial cells should stain (HPA: High in cervical squamous epithelial cells). Use adipose tissue as the negative tissue (HPA: Not detected in adipocytes); on the cervical slide, non-epithelial stromal cells should show only background staining (HPA: High is assigned to squamous epithelial cells).
Positive control tissue: Cervix (Squamous epithelial cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show KRT6A in HaCaT, SiHa, U2OS, hTCEpi, with annotated localisation: Intermediate filaments (enhanced) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a concentration-matched rabbit IgG isotype control for the rabbit primary used in the caption (selected-SKU caption: rabbit primary), plus KRT6A knockout material or a validated peptide-block control to assess antibody specificity (standard IHC practice). Quench endogenous peroxidase and inspect the cervical section for background DAB signal before scoring (selected-SKU caption: peroxidase detection with DAB; standard IHC practice).
⚠️Feasibility: A target-specific fixation window and fixation effect are unreported, and the selected-SKU paraffin-section caption does not state a fixative (selected-SKU caption: fixative not stated). The reported IHC procedure uses heat-mediated retrieval in EDTA at pH 8.0, but its caption does not establish whether retrieval is required for every specimen (selected-SKU caption: EDTA retrieval, pH 8.0). Whether frozen sections or IF are easier is unreported; HPA shows ICC-IF intermediate-filament localization but cautions that its subcellular evidence is based on antibodies targeting proteins from multiple genes (HPA subcellular: intermediate filaments; multiple-gene antibody caution).
HPA tissue IHC evidence for KRT6A
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — High consistency between antibody staining and RNA expression data. Caution, targets protein from more than one gene.). 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 |
|---|---|---|---|---|
| Cervix | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Esophagus | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Nasopharynx | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Oral mucosa | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Skin | Cells in corneal layer | High | 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 → |
| Appendix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced KRT6A IHC Tips
Use the catalog antibody’s paraffin-section IHC conditions as the starting point, then judge staining against KRT6A’s expected epithelial and cytoplasmic pattern.
What should I adjust if KRT6A staining is weak after antigen retrieval?
Start with heat-mediated antigen retrieval in EDTA at pH 8.0 for paraffin sections (datasheet M30943-1). The catalog antibody’s tissue image used this condition before staining a human cervical cancer section (datasheet M30943-1). If signal is weak, check that sections were fully deparaffinized and that the retrieval solution reached the intended heating conditions throughout the run (standard IHC practice). Compare changes in heating duration on adjacent sections while keeping antibody concentration and detection constant (standard IHC practice). Include squamous epithelium as a positive reference, since high staining is reported in cervical squamous epithelial cells (HPA tissue IHC).
Can fixation explain weak or uneven KRT6A staining?
Target-specific sensitivity to fixation is unknown: the selected paraffin-section image does not state its fixative (datasheet M30943-1). Record the fixative and processing history for each specimen before comparing staining intensity across cases (standard IHC practice). Uneven fixation or processing can produce uneven antigen preservation, so examine neighboring sections and tissue morphology before changing the antibody conditions (standard IHC practice). Keep retrieval in EDTA at pH 8.0 as the documented starting condition while comparing specimens (datasheet M30943-1). Do not infer KRT6A fixation tolerance from epithelial staining patterns or its cytoplasmic location (HPA tissue IHC; UniProt P02538).
Where should convincing KRT6A chromogenic staining appear?
Look for cytoplasmic staining in epithelial cells, consistent with the reported KRT6A location and its intermediate filament role (UniProt P02538). The tissue profile describes distinct cytoplasmic staining in squamous and respiratory epithelia (HPA tissue IHC). High staining is reported in cervical, esophageal, oral mucosal and vaginal squamous epithelial cells, giving useful reference compartments (HPA tissue IHC). Compare staining with a counterstained adjacent section when crowded cells make the cytoplasmic boundary difficult to judge (standard IHC practice). Predominantly nuclear or isolated stromal staining warrants review of morphology, background and antibody specificity before it is scored as KRT6A (UniProt P02538; standard IHC practice).
How can I assess whether this stain identifies KRT6A specifically?
KRT6A has 0 annotated isoforms in the supplied record, but that does not establish the antibody’s epitope or gene-level specificity (UniProt P02538). Its intermediate filament rod spans residues 163–476, and the record does not map the catalog antibody’s binding site (UniProt P02538; datasheet M30943-1). The HPA tissue assessment cautions that its antibodies target proteins from more than one gene, so its staining pattern cannot prove KRT6A-only recognition (HPA tissue IHC). Check the catalog antibody’s epitope documentation and relevant validation before assigning a positive cell uniquely to KRT6A (standard IHC practice). Report results as antibody-detected cytokeratin staining when specificity remains unresolved (standard IHC practice).
How should I check KRT6A localisation in a multiplex IF experiment?
Use a separately validated epithelial marker in another channel to identify the expected cell population, then assess whether KRT6A signal occupies its cytoplasm (HPA tissue IHC; standard IF practice). Choose a red or far-red fluorophore after checking autofluorescence in an unstained section, particularly when interpreting weak tissue signal (standard IF practice). Apply permeabilisation appropriate for a cytoplasmic intermediate filament epitope; KRT6A has no transmembrane segment (UniProt P02538; standard IF practice). Include single-stain and secondary-only controls to assess channel bleed-through and background (standard IF practice). HPA reports intermediate filament localisation in IF but cautions that the antibodies behind that result target proteins from multiple genes (HPA subcellular).
What should I check when DAB appears throughout the section?
Compare the specimen with a no-primary control to see whether the signal depends on the primary antibody (standard IHC practice). The catalog image used 10% goat serum blocking, 1:50 primary antibody overnight at 4°C, and an HRP/DAB detection system (datasheet M30943-1). Confirm adequate washing and use an endogenous peroxidase block where the specimen requires one; these are general chromogenic IHC controls (standard IHC practice). Review whether diffuse color follows tissue folds, damaged edges or necrotic areas instead of intact epithelial cytoplasm (standard IHC practice). Treat widespread signal outside the expected epithelial pattern as suspect until controls and morphology support it (HPA tissue IHC; standard IHC practice).
How should I quantify KRT6A staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the epithelial region of interest before scoring, because the reported tissue pattern is concentrated in squamous and respiratory epithelia (HPA tissue IHC). Record the percentage of positive epithelial cells and staining intensity, then calculate an H-score from intensity categories 0–3 if that is your prespecified endpoint (standard IHC practice). Normalize cell counts to the number of evaluable epithelial cells, or report positive-cell density per mm² of evaluable epithelium (standard IHC practice). Exclude folds, necrosis and areas with failed counterstaining using the same rules for every section (standard IHC practice). Compare batches against a consistent positive reference and document any changes in retrieval or detection (standard IHC practice).
How do I distinguish a true KRT6A-positive cell from artefact?
A plausible positive shows cytoplasmic filament-associated staining in an epithelial cell with preserved morphology (UniProt P02538; HPA tissue IHC). High signal in cervical squamous epithelium is a useful reference, while staining in an unexpected compartment or cell type needs closer review (HPA tissue IHC; standard IHC practice). Check whether color is confined to a cut edge, fold or necrotic zone, and compare it with the no-primary control (standard IHC practice). Persistent DAB signal in that control suggests an endogenous enzyme or detection background contribution (standard IHC practice). Interpret positive staining as antibody-detected cytokeratin unless the antibody’s gene-level specificity has been established independently (HPA tissue IHC; standard IHC practice).
Boster reagents
Best KRT6A / Keratin, type II cytoskeletal 6A IHC Antibodies
Human and rat IHC/IF reactivity is cataloged (catalog: applications/reactivity); real IHC data show M30943-1 on a paraffin-embedded human cervical cancer section (M30943-1 image caption).
Real IHC data
Anti-Cytokeratin 6 Rabbit Monoclonal Antibody
Cat # M30943-1
M30943-1 is listed for human IHC and IF/ICC (catalog: applications/reactivity), with an IHC image from paraffin-embedded human cervical cancer tissue (M30943-1 image caption). A04012-2 is listed for human and rat IHC and IF/ICC (catalog: applications/reactivity); no IHC or IF image is supplied for it (catalog: image alts).
Which to pick: For human tissue IHC, choose M30943-1 for its paraffin-section IHC image (M30943-1 image caption); its fixative is unreported (M30943-1 image caption). For human IF/ICC, M30943-1 is a monoclonal option listed for both applications (catalog: clone/applications), although no IF image is supplied (catalog: image alts). For rat IHC or IF/ICC, choose A04012-2 based on its listed rat reactivity and applications (catalog: reactivity/applications); it is polyclonal (catalog: dilution_raw).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P02538 (K2C6A_HUMAN, Keratin, type II cytoskeletal 6A).
- Human Protein Atlas. KRT6A tissue IHC expression (reliability: Supported).
- Human Protein Atlas. KRT6A subcellular location (ICC-IF): Localized to the intermediate filaments. Caution: Based on antibodies targeting proteins from multiple genes..
- Human Protein Atlas. KRT6A antibody validation summary (2 antibodies).
- The interplay between tumor-intrinsic KRT6A and host-derived immune-nutritional status (PNI) defines prognosis in resectable PDAC. Scientific reports 2026 — PMC13469621.
- Keratin 6A Overexpression in the Lymphovascular Invasion-Associated Tumor Subgroup Promotes Progression of Triple-Negative Breast Cancer. Cancer research and treatment 2026 — PMC13382563.
- KRT6A Is a Biomarker of PAS Progression and Enhances the Invasive Ability of Trophoblast Cells. Cells 2026 — PMC13359832.
- Comprehensive pan-cancer analysis of KRT6A as a prognostic and immune biomarker. Scientific reports 2025 — PMC12518557.
- PubMed PMID:7543104 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
- PubMed PMID:6191871 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for KRT6A (Keratin, type II cytoskeletal 6A). Expected localisation Cytoplasm in squamous and respiratory epithelia (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet M30943-1). Validated IHC antibody: M30943-1 at 1:50-1:200 (the product's own IHC validation image is shown). Controls (HPA): positive Cervix (Squamous epithelial cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human cervical cancer tissue; fixative not specified (datasheet M30943-1); 2. Fixation: Image fixative and duration unreported (datasheet M30943-1); 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: EDTA pH 8.0 (datasheet M30943-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet M30943-1); 8. Primary antibody: Rabbit monoclonal (clone GAO-11) anti-KRT6A, 1:50-1:200 (datasheet M30943-1); 9. Primary incubation: Overnight at 4 °C (datasheet M30943-1). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Staining may reflect proteins from more than one gene (HPA tissue IHC); Isoform / epitope: No annotated isoforms; chain starts at residue 2 (UniProt); Regulation: Wound-edge induction (by similarity) (UniProt). Evidence: UniProt P02538, HPA tissue IHC · Supported, HPA ICC-IF · intermediate filaments. Caution: Based on antibodies targeting…, Datasheet M30943-1, PMC13469621, PMC13382563. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/KRT6A/immunohistochemistry-ihc-guide.