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SLK / STE20-like serine/threonine-protein kinase · IHC design guide
Design Immunohistochemistry for SLK
Plan chromogenic SLK IHC in paraffin sections using the catalog antibody’s 2–5 μg/ml range (datasheet A01614-2). Score cytoplasmic staining, using kidney glomerular cells as a high-staining reference (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
SLK 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 | Cytoplasmic tissue staining (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining; high in glomerular cells (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A01614-2) | |
| Positive control | Kidney+4 more · see all | |
| Negative control | None in HPA (detected in all 45 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across compared paraffin sections. (selected-SKU IHC image A01614-2) | |
| Caveat | IHC staining has medium consistency with RNA expression (HPA tissue IHC) | |
| Regulation | Highest in heart and skeletal muscle (UniProt) | |
| Isoform / epitope | 2 isoforms; check antibody epitope coverage (UniProt) |
Section 1
Recommended SLK IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol (datasheet A01614-2) with the published mouse tissue-section IHC protocol for SLK (PMC12423296).
| Sample | Paraffin-embedded human colon tissue; fixative not specified (datasheet A01614-2) |
| Fixation | Image fixative and duration unreported (datasheet A01614-2); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A01614-2); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A01614-2) |
| Primary antibody | Rabbit anti-SLK, 2-5 μg/ml (datasheet A01614-2) |
| Primary incubation | Overnight at 4 °C (datasheet A01614-2) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A01614-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | SLK-positive staining in cells in glomeruli of kidney (HPA tissue IHC: High). HPA tissue profile: General cytoplasmic expression. No signal in the no-primary control. |
💡Decision noteTry heat-mediated EDTA retrieval at pH 8.0 first (datasheet A01614-2); the published protocol used heated citrate at pH 6.0 (PMC12423296).
Section 2
What Is the Expected SLK Staining Pattern?
SLK should stain mainly in the cytoplasm of many cell types (UniProt Q9H2G2: cytoplasm; HPA tissue IHC: general cytoplasmic expression). Kidney glomerular cells show high staining; several glandular and epithelial populations show medium staining (HPA tissue IHC). SLK has no transmembrane segment (UniProt Q9H2G2: topology). HPA rates the tissue IHC profile Approved, with medium consistency between antibody staining and RNA expression (HPA tissue IHC: reliability).
| Cytoplasmic staining in kidney glomerular cells is conspicuous, with preserved cell outlines. | This matches the reported high glomerular signal and general cytoplasmic profile (HPA tissue IHC: kidney, High; profile). Compare cells within the same section before interpreting intensity differences (general IHC practice). |
| Moderate cytoplasmic staining appears in glandular or respiratory epithelial cells. | Medium staining is reported in adrenal, breast, duodenal, endometrial and gallbladder glandular cells, and bronchial respiratory epithelial cells (HPA tissue IHC: Medium). Purkinje cells also show medium staining (HPA tissue IHC: cerebellum, Medium). |
| Strong nuclear-only staining appears while cytoplasm remains unstained. | A nuclear-only pattern conflicts with the cytoplasmic tissue profile and UniProt location (HPA tissue IHC: profile; UniProt Q9H2G2: cytoplasm). Consider nonspecific staining or a scoring error; check the counterstain and detection controls (general IHC practice). |
| The strongest signal occurs in a cell population without a matching reported HPA pattern. | Check whether the signal is cellular and cytoplasmic before calling it SLK (HPA tissue IHC: profile). Cross-reactivity or endogenous detection activity is possible (general IHC practice); an unlisted cell type alone is inconclusive because SLK is ubiquitously expressed (UniProt Q9H2G2: tissue specificity). |
| Staining spreads across stroma, lumens or the whole section without clear cell boundaries. | This distribution is difficult to score as the reported cytoplasmic pattern (HPA tissue IHC: profile). Review background and detection controls before assigning positive cells; diffuse deposition can obscure real cellular signal (general IHC practice). |
💡Expected SLK appearanceCall positive a cell-resolved cytoplasmic signal, especially high in kidney glomerular cells or medium in the listed glandular and epithelial cells (HPA tissue IHC); uniform extracellular staining or isolated nuclear signal warrants review (general IHC practice; UniProt Q9H2G2: cytoplasm).
| Tissue and cell selection | Kidney glomerular cells provide a reported high-signal reference; the listed glandular and epithelial cells provide medium-signal comparisons (HPA tissue IHC: positive tissues). The HPA record lists no negative tissue (HPA tissue IHC: negative list). |
| Validation strength | The tissue profile is Approved but has medium staining-to-RNA consistency (HPA tissue IHC: reliability). HPA015757 is IHC Approved; the supplied record gives no IHC status for HPA056556 (HPA antibodies). |
| Compartment and topology | Use cytoplasm as the primary IHC scoring compartment (UniProt Q9H2G2: subcellular location; HPA tissue IHC: profile). SLK has no transmembrane segment (UniProt Q9H2G2: topology); membrane signal alone is insufficient for a positive IHC call. |
| Isoforms and antibody recognition | Two isoforms are recorded (UniProt Q9H2G2: isoforms 1 and 2). Their relative recognition by the IHC antibody is unspecified in the supplied evidence, so staining intensity cannot establish which isoform is present. |
| IF/ICC interpretation | Can an IF/ICC image be scored by the IHC pattern? Use its separate guide: HPA reports mainly cytosol with additional plasma membrane localisation in ICC-IF (HPA subcellular: approved locations). That observation does not establish an IHC membrane pattern. |
| Situation | Likely cause | Next action |
|---|---|---|
| No cytoplasmic signal in kidney glomerular cells. | The expected high-signal reference is absent (HPA tissue IHC: kidney, High); reagent or detection failure is possible (general IHC practice). | Check the run's positive control, antibody dilution, retrieval and chromogen development against the chosen assay instructions (general IHC practice). No SLK-specific retrieval condition is supplied. |
| Only nuclei appear positive. | Nuclear-only staining disagrees with the reported cytoplasmic location (UniProt Q9H2G2: cytoplasm; HPA tissue IHC: profile). | Inspect the counterstain and include an appropriate detection control; reassess whether the chromogen is truly nuclear (general IHC practice). |
| Many compartments show a uniform haze. | Background may mask the reported cellular cytoplasmic pattern (HPA tissue IHC: profile; general IHC practice). | Review blocking, antibody concentration, washing and detection controls under the assay's general IHC workflow; score only resolved cellular staining (general IHC practice). |
| Unexpected cells stain more strongly than the listed positive cells. | Cross-reactivity or endogenous detection activity is possible (general IHC practice); ubiquitous SLK expression limits any cell-type exclusion (UniProt Q9H2G2: tissue specificity). | Compare cellular localisation and detection controls, then repeat with an independently validated antibody if available (general IHC practice). Do not infer specificity from intensity alone. |
| A listed medium-signal tissue looks weak. | Medium HPA staining is not a guarantee of equal intensity in every section (HPA tissue IHC: listed Medium cells; reliability: medium consistency). | Compare the same run with kidney glomerular cells and inspect section quality and assay controls before changing the score (HPA tissue IHC: kidney, High; general IHC practice). |
| Signal is confined to the cell edge in IHC. | IHC tissue data describe general cytoplasmic expression; additional plasma membrane localisation comes from ICC-IF (HPA tissue IHC: profile; HPA subcellular: approved locations). | Check whether cytoplasm also stains and whether the edge signal persists in detection controls (general IHC practice). Treat membrane-only IHC as unresolved rather than a confirmed SLK pattern. |
Experiment evidence
IHC & IF images showing SLK staining
A01614-2 · IHCIHC analysis of SLK using anti-SLK antibody (A01614-2). SLK was detected in a paraffin-embedded section of human colon tissue. Heat mediated
A01614-2 · IHCIHC analysis of SLK using anti-SLK antibody (A01614-2). SLK was detected in a paraffin-embedded section of human colon tissue. Heat mediated
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000065613-SLK/tissue/cerebral+cortex#imid_4215060
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000065613-SLK/tissue/colon#imid_4214986
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000065613-SLK/tissue/liver#imid_4215003
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000065613-SLK/tissue/kidney#imid_4214996
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA015757; green = SLK, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA015757; green = SLK, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for SLK IHC & IF
🧪Run kidney first and score the glomerular cells, where SLK staining is High (HPA: High in kidney cells in glomeruli). HPA detects SLK in all 45 scored tissues, so there is no supported negative tissue; use no-primary and isotype controls to define background, and treat any unstained cells within the kidney section as internal background observations rather than a validated SLK-negative population (HPA: no negative rows; detected in all 45 scored tissues).
Positive control tissue: Kidney (Cells in glomeruli, HPA High)
Negative control tissue: None in HPA: SLK is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show SLK in A-431, U-251MG, U2OS, ASC52telo, RPTEC/TERT1, hTERT-RPE1 (serum starved), with annotated localisation: Cytosol (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only slide; a host- and clonality-matched rabbit IgG isotype control, using the catalog antibody’s actual clonality; and SLK-knockout material or a validated immunogen-peptide block as a biological specificity control (caption: rabbit anti-SLK; clonality unreported; standard IHC controls). For kidney chromogenic IHC, quench endogenous peroxidase and check background before scoring glomerular staining (HPA: kidney cells in glomeruli High; standard IHC practice).
⚠️Feasibility: The selected IHC caption reports paraffin-embedded human colon, heat retrieval in EDTA at pH 8.0, and 2 μg/ml primary antibody overnight at 4°C; it does not report the fixative, so a target-specific fixation window or fixation effect is unreported (caption: A01614-2). The caption supports trying that retrieval condition but does not establish that retrieval is required for every specimen (caption: EDTA heat retrieval). HPA provides ICC-IF images and reports mainly cytosolic SLK with additional plasma-membrane localization, but the supplied evidence does not establish that frozen sections or IF are easier than paraffin IHC; assess kidney peroxidase background when scoring chromogenic staining (HPA: SLK subcellular; standard IHC practice).
HPA tissue IHC evidence for SLK
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Medium 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 |
|---|---|---|---|---|
| Kidney | Cells in glomeruli | High | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | Medium | Protein (IHC) | HPA → |
| Breast | Glandular cells | Medium | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Medium | Protein (IHC) | HPA → |
| Cerebellum | Purkinje cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: SLK is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced SLK IHC Tips
Troubleshoot SLK staining in paraffin sections by checking retrieval, tissue controls, cytoplasmic localisation, and scoring before interpreting signal (datasheet A01614-2; HPA tissue IHC).
How should I adjust retrieval when SLK staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A01614-2). The demonstrated staining used 2 μg/ml catalog antibody overnight at 4°C in human colon, so keep antibody concentration and detection conditions stable while assessing retrieval (datasheet A01614-2). Compare serial sections for signal in cells and background, documenting heating duration and section integrity for each run. If staining remains weak, test an alternative retrieval buffer as a fallback on matched sections; its performance for this antibody is unreported in the supplied evidence. Include a no-primary control to distinguish retrieval-related background from SLK signal.
Could fixation explain inconsistent SLK staining between paraffin sections?
Target-specific fixation sensitivity for SLK is unknown because the catalog tissue-IHC caption identifies a paraffin section but does not state its fixative (datasheet A01614-2). Record the fixative, fixation duration, processing history, and section age for every specimen before comparing staining. Use similarly processed serial sections to assess whether differences persist under the documented EDTA pH 8.0 retrieval and 2 μg/ml antibody conditions (datasheet A01614-2). Uneven preservation can change morphology and staining in paraffin sections, so examine tissue integrity alongside signal intensity. Do not assign a particular fixation effect to SLK without a direct comparison under controlled processing conditions.
Where should SLK staining appear in tissue sections?
Expect predominantly cytoplasmic staining: tissue IHC reports general cytoplasmic expression, and subcellular imaging places SLK mainly in the cytosol with an additional plasma-membrane location (HPA tissue IHC; HPA subcellular). UniProt likewise annotates cytoplasmic localisation and no transmembrane segment (UniProt Q9H2G2). Evaluate staining within intact cells using a counterstain to locate nuclei and tissue boundaries. A sharp membrane-associated component can be compatible with the reported additional location, but judge it against the dominant cytoplasmic pattern and matched controls (HPA subcellular). Predominantly nuclear or extracellular staining warrants review of background, morphology, and antibody specificity before scoring.
How can epitope choice change what SLK IHC detects?
SLK has 2 annotated isoforms, while the supplied catalog tissue-IHC caption does not identify the antibody epitope or establish isoform coverage (UniProt Q9H2G2; datasheet A01614-2). Map the immunogen or epitope against both isoform sequences before calling staining isoform-specific. The protein includes a kinase domain at residues 34–292 and a UVR domain at 875–910, with annotated phosphorylation sites including residues 183 and 189 (UniProt Q9H2G2). Those features identify regions to check during mapping; they do not demonstrate that this antibody distinguishes phosphorylation states. Use an independently mapped antibody or a suitable specificity control when an isoform-level conclusion matters.
How should I assess SLK by multiplex IF in tissue?
For the separate IF/ICC workflow, pair SLK with a marker identifying the cell population being scored; glomerular cells offer a tissue-IHC population with reported high staining (HPA tissue IHC). Choose spectrally separated fluorophores and consider a far-red SLK channel if tissue autofluorescence compromises shorter wavelengths. SLK is mainly cytosolic, with an additional plasma-membrane location, but the catalog antibody’s epitope side is not supplied (HPA subcellular; datasheet A01614-2). Once epitope accessibility is established, assess whether permeabilisation is needed for cytosolic detection and preserve membrane detail when evaluating peripheral signal. Include single-channel, no-primary, and autofluorescence controls before interpreting colocalisation.
What should I check when DAB background obscures SLK staining?
The documented paraffin-section example used 10% goat-serum blocking, 2 μg/ml rabbit primary overnight at 4°C, and peroxidase-linked detection with DAB (datasheet A01614-2). First inspect a no-primary control and assess whether deposit follows tissue edges, damaged areas, or the intended cellular pattern. An endogenous-peroxidase block and careful washing are general chromogenic IHC steps; assess their effectiveness in the tissue under study. If background persists, compare a small primary-antibody titration while holding retrieval and development time constant. Score only interpretable cellular signal against matched controls, since HPA describes the tissue pattern as generally cytoplasmic (HPA tissue IHC).
How should I quantify SLK staining across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and tissue compartment before scoring, because SLK shows general cytoplasmic tissue staining and varies across reported cell populations (HPA tissue IHC). For cellular intensity, calculate an H-score from the percentages of cells at intensity 0–3, yielding a 0–300 scale; also report the percentage of positive cells. For spatial comparisons, report positive-cell density per mm² of viable tissue and exclude damaged or necrotic regions. Normalise comparisons to the same cell population, evaluable area, staining batch, and scoring threshold. Keep retrieval, antibody concentration, DAB development, and image acquisition consistent, then review representative sections for morphology and background.
How can I distinguish credible SLK signal from artefact?
Credible SLK staining should fit the reported general cytoplasmic tissue pattern; cytosolic signal with some plasma-membrane localisation is also supported by subcellular imaging (HPA tissue IHC; HPA subcellular). Check the stained cell population against the tissue context: HPA reports high staining in kidney glomerular cells and low staining in lung macrophages (HPA tissue IHC). Predominantly nuclear staining, isolated tissue-edge deposits, and signal confined to necrotic areas require closer review before interpretation. Use a no-primary control and an endogenous-peroxidase block to assess nonspecific DAB deposition as general IHC checks. Treat staining and expression agreement cautiously because the tissue-IHC reliability assessment reports medium consistency with RNA data (HPA tissue IHC).
Boster reagents
Best SLK / STE20-like serine/threonine-protein kinase IHC Antibodies
Real SLK IHC images are available for human paraffin colon and colon adenocarcinoma sections (A01614-2 IHC captions); no IF data are provided (catalog: A01614-2).
Real IHC data
Anti-SLK Antibody ®
Cat # A01614-2
A01614-2 is listed for IHC and reacts with human and mouse samples (catalog: A01614-2 applications and reactivity). Its IHC images show human paraffin colon and colon adenocarcinoma sections (A01614-2 IHC captions).
Which to pick: Choose A01614-2 for human paraffin-section IHC with chromogenic detection (A01614-2 IHC captions: HRP and DAB). No listed SKU has IF/ICC validation (catalog: A01614-2 applications and IF images). A01614-2 lists mouse reactivity, but its IHC images document human sections only; the fixative is unreported (catalog: A01614-2 reactivity; A01614-2 IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q9H2G2 (SLK_HUMAN, STE20-like serine/threonine-protein kinase).
- Human Protein Atlas. SLK tissue IHC expression (reliability: Approved).
- Human Protein Atlas. SLK subcellular location (ICC-IF): Mainly localized to the cytosol. In addition localized to the plasma membrane..
- Human Protein Atlas. SLK antibody validation summary (2 antibodies).
- Estrogen Promotes Endometrial Cancer Development by Modulating ZNF626, SLK, and RFWD3 Gene Expression and Inducing Immune Inflammatory Changes. Biomedicines 2025 — PMC11853163.
- Dysregulated RNA splicing impairs regeneration in alcohol-associated liver disease. Nature communications 2025 — PMC12423296.
- Circuit-selective cell-autonomous regulation of inhibition in pyramidal neurons by Ste20-like kinase. Cell reports 2022 — PMC9756112.
- Deletion of the Ste20-like kinase SLK in skeletal muscle results in a progressive myopathy and muscle weakness. Skeletal muscle 2017 — PMC5288853.
- PubMed PMID:10699464 — UniProt-cited evidence.
- PubMed PMID:11149944 — UniProt-cited evidence.
- PubMed PMID:9039502 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for SLK (STE20-like serine/threonine-protein kinase). Expected localisation Cytoplasmic tissue staining (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A01614-2). Validated IHC antibody: A01614-2 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Kidney (Cells in glomeruli); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human colon tissue; fixative not specified (datasheet A01614-2); 2. Fixation: Image fixative and duration unreported (datasheet A01614-2); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat retrieval: EDTA pH 8.0 (datasheet A01614-2); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A01614-2); 8. Primary antibody: Rabbit anti-SLK, 2-5 μg/ml (datasheet A01614-2); 9. Primary incubation: Overnight at 4 °C (datasheet A01614-2). Watch for: Fixation: Keep fixation consistent across compared paraffin sections. (selected-SKU IHC image A01614-2); Caveat: IHC staining has medium consistency with RNA expression (HPA tissue IHC); Isoform / epitope: 2 isoforms; check antibody epitope coverage (UniProt); Regulation: Highest in heart and skeletal muscle (UniProt). Evidence: UniProt Q9H2G2, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the cytosol. In addition localized to the plasma…, Datasheet A01614-2, PMC12423296. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/SLK/immunohistochemistry-ihc-guide.