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KRT9 / Keratin, type I cytoskeletal 9 · IHC design guide
Design Immunohistochemistry for KRT9
Plan chromogenic KRT9 IHC in paraffin sections using sole epidermis as a positive tissue (HPA tissue IHC). The catalog antibody has a paraffin IHC example (datasheet M03692); assess epidermal staining without assuming a subcellular pattern (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
KRT9 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 | Sole epidermal cells; compartment unreported (HPA tissue IHC) | |
| Staining pattern | High staining in sole epidermal cells; subcellular pattern unreported (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet M03692) | |
| Positive control | Sole of foot | |
| 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); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image M03692) | |
| Caveat | Sampling outside sole may miss the restricted tissue signal (HPA tissue IHC) | |
| Regulation | Expression tracks terminal palmoplantar differentiation (UniProt) | |
| Isoform / epitope | No annotated isoforms or cleavage; epitope region unspecified (UniProt) |
Section 1
Recommended KRT9 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by published KRT9 protocols for mouse footpad epidermis (PMC3923277) and melanoma and nevus tissue (PMC9470607).
| Sample | Paraffin-embedded human skin cancer tissue; fixative not specified (datasheet M03692) |
| Fixation | Image fixative and duration unreported (datasheet M03692); 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 M03692); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet M03692) |
| Primary antibody | Rabbit monoclonal (clone GGH-11) anti-KRT9, 1:50 (datasheet M03692) |
| Primary incubation | Overnight at 4 °C (datasheet M03692) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet M03692) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | KRT9-positive staining in epidermal cells of sole of foot (HPA tissue IHC: High). HPA tissue profile: Exclusively expressed in sole of foot. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA retrieval at pH 8.0 for the catalog antibody (datasheet M03692).
Section 2
What Is the Expected KRT9 Staining Pattern?
KRT9 is a structural keratin of suprabasal palmoplantar epidermal cells, where cytoplasmic filament staining is expected (UniProt P35527 function). It has no transmembrane segment; UniProt does not annotate a subcellular location (UniProt P35527 topology; UniProt P35527 subcellular record). Sole-of-foot epidermal cells stain at a high level, with HPA reliability rated Supported (HPA tissue IHC).
| Strong staining follows the suprabasal epidermal layers in a sole-of-foot section (HPA tissue IHC; UniProt P35527 function). | This fits the reported high signal in sole epidermal cells and KRT9's filament role in suprabasal palmoplantar keratinocytes (HPA tissue IHC; UniProt P35527 function). Judge the epidermal layer and cytoplasmic pattern together; intensity alone is insufficient (general IHC practice). |
| Signal is mainly nuclear or outlines cell membranes instead of the cytoplasm (UniProt P35527 function; UniProt P35527 topology). | Treat this as a localization mismatch requiring review, since KRT9 forms intermediate filament networks and has no transmembrane segment (UniProt P35527 function; UniProt P35527 topology). Check morphology and the negative control before assigning it to KRT9 (general IHC practice). |
| Adipocytes or respiratory epithelial cells stain conspicuously (HPA tissue IHC). | HPA reports KRT9 as not detected in the sampled adipocytes and bronchial respiratory epithelial cells (HPA tissue IHC). Consider cross-reactivity or endogenous chromogen-generating activity; compare a negative control and verify which cells are stained (general IHC practice). |
| Chromogen spreads across stroma, section edges, and epidermis without a clear cellular pattern (general IHC practice). | Diffuse background does not establish KRT9 expression (general IHC practice). Review reagent background, blocking, washing, and chromogen development, then compare with the expected sole epidermal distribution (general IHC practice; HPA tissue IHC). |
| No epidermal signal appears in a sole-of-foot section (HPA tissue IHC). | This conflicts with HPA's high sole epidermal staining, but a single negative section cannot identify the cause (HPA tissue IHC; general IHC practice). Confirm epidermis is present and examine the positive control and staining run (general IHC practice). |
💡Expected KRT9 appearanceCall KRT9 positive when sole epidermal cells show high, predominantly cytoplasmic staining consistent with suprabasal filaments; isolated nuclear, membranous, or widespread non-epidermal chromogen is suspect (HPA tissue IHC; UniProt P35527 function and topology; general IHC practice).
| Tissue and layer selection | UniProt places KRT9 in terminally differentiated palm-and-sole epidermis; HPA directly reports high staining in sole epidermal cells (UniProt P35527 tissue specificity; HPA tissue IHC). Use a section containing intact sole epidermis to assess this reported pattern (general IHC practice). |
| Location of the target | The intermediate-filament rod and keratin assembly function support a cytoplasmic filament interpretation, while UniProt supplies no explicit subcellular-location annotation (UniProt P35527 domain, function, and subcellular record). Do not assign a more precise organelle location from these records. |
| Strength of antibody evidence | HPA rates IHC for HPA007261 and CAB037322 as Supported, and the tissue profile itself as Supported (HPA antibody validation; HPA tissue IHC). That rating includes external characterization, with no internal RNA data available for staining correlation (HPA tissue IHC). |
| Tissue RNA versus protein staining | HPA lists RNA as tissue enriched in lymphoid tissue while its reported protein staining is exclusive to sole of foot (HPA tissue IHC). Do not infer lymphoid-cell IHC positivity from that RNA label; score the observed cells against the reported protein pattern (HPA tissue IHC; general IHC practice). |
| IF/ICC Q&A: Is a cellular IF pattern established? | No. HPA provides no main subcellular location or ICC-IF image-bearing cell lines; its HaCaT value of 15.9 nTPM is expression data, not an IF localization result (HPA subcellular record). Interpret any IF result against appropriate controls (general IF practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| Sole epidermis is unstained (HPA tissue IHC). | The section may lack assessable epidermis, or the staining run may have failed (general IHC practice). | Inspect morphology, run a sole epidermal positive control, and review the catalog antibody's IHC-P conditions before interpreting absence (HPA tissue IHC; general IHC practice). |
| Sole epidermis stains weakly relative to the reported high level (HPA tissue IHC). | Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation. | Compare controls and review retrieval, antibody dilution, and detection settings under the validated IHC-P workflow (general IHC practice). |
| The strongest staining is nuclear or membranous (UniProt P35527 function and topology). | This distribution is inconsistent with the expected keratin filament interpretation (UniProt P35527 function). | Check cell boundaries and counterstain, then compare a negative control and a sole epidermal positive control (general IHC practice; HPA tissue IHC). |
| Adipocytes or bronchial respiratory epithelium stain (HPA tissue IHC). | These sampled cell types are reported as not detected; cross-reactivity or endogenous detection activity is possible (HPA tissue IHC; general IHC practice). | Verify cell identity, compare reagent controls, and assess endogenous peroxidase blocking for chromogenic detection (general IHC practice). |
| Background obscures the epidermal layers (general IHC practice). | Nonspecific reagent binding, incomplete washing, or excess chromogen development may reduce contrast (general IHC practice). | Review blocking, washes, antibody dilution, and development time; require a discernible epidermal cell pattern (general IHC practice; HPA tissue IHC). |
| A proposed positive call rests only on lymphoid-tissue RNA enrichment (HPA tissue IHC). | The RNA label and reported tissue protein pattern differ, and HPA lacks internal RNA correlation for staining (HPA tissue IHC). | Base the IHC call on slide staining and controls; use sole epidermis as the reported positive comparator (HPA tissue IHC; general IHC practice). |
Experiment evidence
IHC & IF images showing KRT9 staining
M03692 · IHCIHC analysis of KRT9 using anti-KRT9 antibody (M03692). KRT9 was detected in a paraffin-embedded section of human skin cancer tissue. Heat m
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000171403-KRT9/tissue/cerebral+cortex#imid_20135781
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000171403-KRT9/tissue/colon#imid_20135699
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000171403-KRT9/tissue/liver#imid_20135708
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000171403-KRT9/tissue/kidney#imid_20135701
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for KRT9 IHC & IF
🧪Run sole-of-foot skin first: epidermal cells should stain strongly (HPA: High in sole-of-foot epidermal cells). Use adipose tissue as a negative, where adipocytes are not detected (HPA: Not detected in adipose-tissue adipocytes); dermal cells on the sole slide should remain unstained as an internal background check (UniProt P35527: expression in terminally differentiated palmoplantar epidermis).
Positive control tissue: Sole of foot (Epidermal cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for KRT9; derive a cell-line control from the positive tissue's cell type (Epidermal cells) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary, secondary-only control and a rabbit IgG isotype control matched to the primary antibody’s clonality where known (selected M03692 caption: rabbit primary and anti-rabbit secondary); use KRT9 knockout material or an immunogen-peptide block, if available, to test target specificity. Quench endogenous peroxidase for HRP/DAB detection, and check epidermal autofluorescence if adapting the assay to IF (selected M03692 caption: HRP/DAB detection).
⚠️Feasibility: A target-specific fixation window and fixation effect are unreported, and the selected M03692 paraffin-section caption does not state the fixative (selected M03692 caption). That caption uses heat retrieval in EDTA at pH 8.0, but it does not establish whether retrieval is required or whether frozen sections or IF are easier (selected M03692 caption). In sole skin, inspect the thick cornified layer for nonspecific signal before scoring epidermal cells (HPA: High in sole-of-foot epidermal cells; standard IHC practice).
HPA tissue IHC evidence for KRT9
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — No tissue staining or RNA expression data available for comparison. External characterization data supports antibody staining but no internal RNA data available for correlation.). 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 |
|---|---|---|---|---|
| Sole of foot | Epidermal cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | 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 → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced KRT9 IHC Tips
Troubleshoot chromogenic KRT9 IHC in paraffin sections against its expected palmoplantar epidermal pattern, using the catalog antibody’s tissue staining conditions as a starting point.
How should I adjust retrieval when KRT9 staining is weak in paraffin sections?
Use heat-mediated antigen retrieval in EDTA buffer at pH 8.0 for paraffin sections (datasheet M03692). The selected tissue-IHC caption pairs that retrieval with a 1:50 primary antibody dilution and overnight incubation at 4°C, so assess retrieval while holding those steps constant (datasheet M03692). If signal remains weak, compare modestly shorter and longer heating intervals on adjacent sections, checking whether epidermal structure and nuclear detail remain intact (standard IHC practice). Include sole-of-foot epidermis as a positive control because its epidermal cells stain strongly for KRT9 (HPA: sole-of-foot epidermal cells, High). Record the heating interval and staining pattern for each section before changing antibody concentration (standard IHC practice).
Could fixation explain absent KRT9 staining in my paraffin sections?
Target-specific KRT9 sensitivity to fixation is unknown: the selected tissue-IHC caption reports a paraffin-embedded section but does not state its fixative (datasheet M03692). Document the specimen’s actual fixative and fixation duration, then compare sections processed under known, consistent conditions before attributing a negative result to KRT9 biology (standard IHC practice). Run a sole-of-foot epidermal control through the same processing and staining batch; strong epidermal staining is the expected positive pattern (HPA: sole-of-foot epidermal cells, High). If both control and specimen are negative, inspect retrieval, primary antibody incubation, and detection before interpreting the specimen (standard IHC practice). Do not infer a KRT9 fixation effect from its filament function or phosphorylation sites (UniProt P35527).
Where should convincing KRT9 signal appear in a tissue section?
Expect KRT9 signal in suprabasal keratinocytes of palmoplantar epidermis, consistent with its role in intermediate filament networks (UniProt P35527). Sole-of-foot epidermal cells provide a strong tissue reference, while the HPA tissue profile describes expression as exclusive to sole of foot (HPA: sole-of-foot epidermal cells, High; HPA: tissue profile). Evaluate staining within viable epidermal cells and compare its distribution with the section’s morphology rather than treating diffuse surface colour as cellular signal (standard IHC practice). The selected catalog image reports staining in paraffin-embedded human skin cancer tissue, but that caption alone does not establish the identity of every stained cell (datasheet M03692).
Could an epitope or KRT9 variant account for uneven staining?
The supplied record lists one KRT9 chain spanning residues 1–623 and no annotated isoforms, so an isoform-specific explanation needs independent evidence (UniProt P35527). Its intermediate filament rod spans residues 153–465, with reported phosphoserines at 14 and 57; the antibody epitope is not mapped in the supplied material (UniProt P35527; datasheet M03692). Consequently, do not assign weak staining to phosphorylation or epitope masking without a direct comparison (standard IHC interpretation). Compare adjacent sections with the documented EDTA pH 8.0 retrieval and matched detection, then assess whether changes preserve the expected suprabasal epidermal pattern (datasheet M03692; UniProt P35527).
How can I check KRT9 localisation by IF alongside chromogenic IHC?
For IF multiplexing, pair KRT9 with a marker that identifies suprabasal keratinocytes, the expected KRT9-bearing cells in palmoplantar epidermis (UniProt P35527). Choose spectrally separated fluorophores and consider a far-red channel if tissue autofluorescence obscures shorter wavelengths; include an unstained section to map that background (standard IF practice). KRT9 forms intracellular intermediate filaments and has no transmembrane segment, so permeabilisation should permit antibody access to a cytoplasmic filament epitope (UniProt P35527). Optimise permeabilisation against retained cell morphology and include single-colour controls when interpreting overlap (standard IF practice). The supplied HPA subcellular record has no ICC/IF images to corroborate a particular cellular pattern (HPA: subcellular record).
What should I check when brown staining appears outside the expected epidermis?
Start by comparing the distribution with viable suprabasal palmoplantar epidermis, where KRT9 is expected, and with a no-primary control (UniProt P35527; standard IHC practice). The catalog caption used 10% goat serum blocking, 1:50 primary antibody overnight at 4°C, a peroxidase-conjugated secondary for 30 minutes at 37°C, and DAB development (datasheet M03692). Check whether background rises with primary concentration or DAB development time on matched sections (standard IHC practice). Use an endogenous peroxidase block and inspect no-primary staining before assigning brown deposits to KRT9; these are general chromogenic IHC controls, not KRT9-specific evidence (standard IHC practice).
How should I score KRT9 staining across epidermal samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the region of interest as viable epidermis and score its suprabasal keratinocytes, the expected KRT9-expressing compartment (UniProt P35527). Report the percentage of positive cells and an intensity-weighted H-score from 0–300, with intensity categories and positivity threshold set before reviewing groups (standard IHC scoring practice). Normalise cell counts to the number of assessable suprabasal keratinocytes, or report stained area per mm² of viable epidermis when using image analysis (standard IHC quantification practice). Exclude folds, torn edges, necrotic regions, and surface deposits using the same criteria for every section (standard IHC practice). Include a consistently processed sole-of-foot control to track staining performance between runs (HPA: sole-of-foot epidermal cells, High; standard IHC practice).
How can I distinguish true KRT9 staining from artefact?
A convincing result follows viable suprabasal keratinocytes in palmoplantar epidermis, matching KRT9’s intermediate filament function and tissue specificity (UniProt P35527). Compare the candidate signal with a sole-of-foot positive control, where epidermal staining is high, and a no-primary control (HPA: sole-of-foot epidermal cells, High; standard IHC practice). Treat isolated staining in an unexpected cell type or compartment, or colour concentrated at section edges and necrotic areas, as requiring further checks (UniProt P35527; standard IHC interpretation). If brown signal persists without primary antibody, investigate endogenous enzyme activity and detection background before calling it KRT9 positive (standard chromogenic IHC practice).
Boster reagents
Best KRT9 / Keratin, type I cytoskeletal 9 IHC Antibodies
M03692 has real IHC data from a paraffin-embedded human skin cancer section (M03692 image caption); its listed reactivity covers human, mouse, and rat (M03692 catalog).
Real IHC data
Anti-Cytokeratin 9 KRT9 Rabbit Monoclonal Antibody
Cat # M03692
M03692 was demonstrated by IHC on a paraffin-embedded human skin cancer section at 1:50 (M03692 image caption). It is a rabbit monoclonal antibody listed for IHC, IP, and WB, with human, mouse, and rat reactivity (M03692 catalog).
Which to pick: For tissue IHC, choose M03692: its own image documents chromogenic staining of a paraffin-embedded human section after EDTA retrieval at pH 8.0; the fixative is unreported (M03692 image caption). No SKU in the payload lists IF/ICC or provides an IF image, so there is no supported IF/ICC pick here (M03692 catalog). For cross-species work, M03692 lists mouse and rat reactivity alongside human, but its IHC image demonstrates human tissue only (M03692 catalog; M03692 image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P35527 (K1C9_HUMAN, Keratin, type I cytoskeletal 9).
- Human Protein Atlas. KRT9 tissue IHC expression (reliability: Supported).
- Human Protein Atlas. KRT9 subcellular location (ICC-IF): Highest expression in HaCaT: 15.9 nTPM.
- Human Protein Atlas. KRT9 antibody validation summary (2 antibodies).
- Keratin 9 is required for the structural integrity and terminal differentiation of the palmoplantar epidermis. The Journal of investigative dermatology 2014 — PMC3923277.
- The use of ectopic volar fibroblasts to modify skin identity. Science (New York, N.Y.) 2024 — PMC11457755.
- Protein expression of prognostic genes in primary melanoma and benign nevi. Journal of cancer research and clinical oncology 2022 — PMC9470607.
- PubMed PMID:7507869 — UniProt-cited evidence.
- PubMed PMID:7512862 — UniProt-cited evidence.
- PubMed PMID:16625196 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for KRT9 (Keratin, type I cytoskeletal 9). Expected localisation Sole epidermal cells; compartment unreported (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet M03692). Validated IHC antibody: M03692 at 1:50 (the product's own IHC validation image is shown). Controls (HPA): positive Sole of foot (Epidermal cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human skin cancer tissue; fixative not specified (datasheet M03692); 2. Fixation: Image fixative and duration unreported (datasheet M03692); 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 M03692); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet M03692); 8. Primary antibody: Rabbit monoclonal (clone GGH-11) anti-KRT9, 1:50 (datasheet M03692); 9. Primary incubation: Overnight at 4 °C (datasheet M03692). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image M03692); Caveat: Sampling outside sole may miss the restricted tissue signal (HPA tissue IHC); Isoform / epitope: No annotated isoforms or cleavage; epitope region unspecified (UniProt); Regulation: Expression tracks terminal palmoplantar differentiation (UniProt). Evidence: UniProt P35527, HPA tissue IHC · Supported, HPA cell-line RNA · Highest expression in HaCaT: 15.9 nTPM, Datasheet M03692, PMC3923277, PMC9470607. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/KRT9/immunohistochemistry-ihc-guide.