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SIK2 / Serine/threonine-protein kinase SIK2 · IHC design guide
Design Immunohistochemistry for SIK2
Plan SIK2 paraffin IHC around cytoplasmic staining in most tissues (HPA tissue IHC). Compare medium staining in cerebral cortex neuronal cells with undetected lymph node germinal center cells (HPA tissue IHC), and interpret staining intensity cautiously because agreement with RNA expression is low (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
SIK2 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); ER membrane location (UniProt) | |
| Staining pattern | Cytoplasmic staining in most tissues (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A04515-1) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | Bone marrow+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 has low consistency with RNA expression (HPA tissue IHC) | |
| Regulation | Low tissue specificity (HPA RNA specificity) | |
| Isoform / epitope | 0 isoforms; no processing or extracellular domain (UniProt) |
Section 1
Recommended SIK2 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by published IHC methods for HCC specimens, paraffin pathology sections, spinal cord tissue, and tumor sections (PMC12528092; PMC5955149; PMC12676768; PMC9353504).
| Sample | Paraffin-embedded mouse brain tissue; fixative not specified (datasheet A04515-1) |
| Fixation | Image fixative and duration unreported (datasheet A04515-1); 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 A04515-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A04515-1) |
| Primary antibody | Rabbit anti-SIK2, 2-5 μg/ml (datasheet A04515-1) |
| Primary incubation | Overnight at 4 °C (datasheet A04515-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A04515-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | SIK2-positive staining in glandular cells of adrenal gland (HPA tissue IHC: Medium). HPA tissue profile: Cytoplasmic expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with EDTA pH 8.0 heat retrieval for the catalog antibody (datasheet A04515-1). Published alternatives use microwave heating or boiling water (PMC12528092; PMC9353504).
Section 2
What Is the Expected SIK2 Staining Pattern?
In paraffin-section IHC, expect predominantly cytoplasmic SIK2 staining, including medium staining in adrenal glandular cells and cortical neurons (HPA tissue IHC). UniProt also places SIK2 at the endoplasmic reticulum membrane, with no transmembrane segment (UniProt Q9H0K1). HPA rates the tissue antibody Approved but reports low consistency between staining and RNA expression; use the listed cell patterns as guides, not absolute rules (HPA tissue IHC).
| Cytoplasmic signal in adrenal glandular cells or cerebral cortical neurons. | This matches HPA's medium-staining examples and its predominantly cytoplasmic tissue profile (HPA tissue IHC). Compare staining within the named cells before judging an entire section positive; adjacent cell populations need not share the same appearance (HPA tissue IHC). |
| Predominantly nuclear chromogen in a tissue section, with little cytoplasmic signal. | This departs from the reported tissue-IHC pattern and warrants a localisation check (HPA tissue IHC). Nuclear localisation alone does not settle specificity: nucleoplasm is an approved location in HPA ICC-IF images, a different application (HPA subcellular ICC-IF). |
| Strong signal in germinal-center cells or bone-marrow hematopoietic cells. | HPA lists these cells as not detected, so assess cross-reactivity and endogenous chromogenic activity with detection controls (HPA tissue IHC; general IHC practice). Because tissue-antibody staining has low consistency with RNA, an unexpected result is a prompt to verify, not proof of an artefact (HPA tissue IHC). |
| Uniform haze across cells, stroma, and nominally negative regions. | A pattern without cell or compartment definition is hard to interpret as SIK2; examine primary-omission and detection controls for nonspecific background (general IHC practice). HPA's reported pattern is cytoplasmic expression in most tissues, with differences among named cell populations (HPA tissue IHC). |
| No signal in adrenal glandular cells despite interpretable section morphology. | HPA reports medium staining there, making this a useful failed-signal check rather than a guaranteed positive control (HPA tissue IHC). Review the catalog antibody's IHC-P instructions, detection reagents, and a parallel control section (general IHC practice); note HPA's low RNA–staining consistency (HPA tissue IHC). |
💡Expected SIK2 appearanceCall a result consistent with the reference pattern when cytoplasmic chromogen is discernible at roughly medium intensity in HPA-listed cells such as adrenal glandular cells, while uniform haze or isolated staining of HPA-listed undetected cells prompts verification (HPA tissue IHC; general IHC practice).
| Tissue and cell choice | HPA reports medium staining in adrenal glandular cells, breast myoepithelial cells, and cortical neurons, but low staining in kidney tubule cells and adipocytes (HPA tissue IHC). Choose a named medium-staining population when checking assay performance. |
| Strength of tissue-IHC evidence | The tissue antibody is Approved, with low consistency between staining and RNA; its IHC status is Approved, while a separate antibody has Approved ICC status (HPA tissue IHC; HPA antibodies). Do not treat these statuses as interchangeable application validation. |
| Compartment and topology | HPA tissue IHC describes cytoplasmic expression in most tissues; UniProt lists cytoplasm and endoplasmic reticulum membrane and no transmembrane segment (HPA tissue IHC; UniProt Q9H0K1). These annotations guide interpretation but do not specify a chromogenic retrieval condition. |
| IF/ICC Q&A: should its nuclear and vesicular pattern govern this IHC readout? | No. HPA approves nucleoplasm and vesicles as main ICC-IF locations, with cytosol among additional locations (HPA subcellular ICC-IF). Interpret paraffin-section chromogen against the tissue-IHC cytoplasmic profile; the applications show different reported patterns (HPA tissue IHC). |
| Processing and epitope uncertainty | UniProt lists one 1–926 chain, no signal peptide or propeptide, no annotated isoforms, and phosphorylation and acetylation sites (UniProt Q9H0K1). The payload does not locate the antibody epitope, so it cannot predict retrieval response or modification-dependent staining. |
| Chromogenic detection | Endogenous activity and nonspecific detection can create colour independent of primary-antibody binding (general IHC practice). Use appropriate detection controls when signal appears in HPA-listed undetected cells; those examples are reference observations, not universal biological negatives (HPA tissue IHC). |
| Situation | Likely cause | Next action |
|---|---|---|
| Adrenal glandular cells show no convincing cytoplasmic signal. | A missed assay step or weak detection is possible (general IHC practice); HPA's medium result is an observed reference, not a guarantee for every section (HPA tissue IHC). | Check the catalog antibody's IHC-P instructions and reagent performance, then compare a parallel named positive tissue and detection control (general IHC practice; HPA tissue IHC). |
| Chromogen appears mainly in nuclei. | The compartment differs from HPA's predominant tissue-IHC pattern, although nucleoplasm is approved in ICC-IF (HPA tissue IHC; HPA subcellular ICC-IF). | Check cell identity, counterstain, and primary-omission control before interpreting nuclear signal as SIK2 in paraffin sections (general IHC practice). |
| Germinal-center cells stain strongly. | HPA reports these cells as not detected; cross-reactivity or endogenous detection activity may explain discordant colour (HPA tissue IHC; general IHC practice). | Compare primary-omission and detection controls, then review whether cytoplasmic staining also occurs in a named medium-staining cell population (general IHC practice; HPA tissue IHC). |
| Colour coats most of the section without clear cell boundaries. | Diffuse background can arise from nonspecific antibody or detection binding (general IHC practice), obscuring the cell-level pattern reported by HPA (HPA tissue IHC). | Review blocking, washing, and antibody concentration under the catalog IHC-P instructions; judge the result against a primary-omission control (general IHC practice). |
| Kidney tubules look faint beside adrenal glandular cells. | This can reflect HPA's low kidney-tubule versus medium adrenal-glandular staining observations (HPA tissue IHC). | Score each named cell population against its own reference level; avoid using a low-staining population alone to declare assay failure (HPA tissue IHC). |
| Staining disagrees with an RNA-based expectation. | HPA explicitly reports low consistency between tissue-antibody staining and RNA expression despite an Approved reliability label (HPA tissue IHC). | Document cell type, compartment, and controls; interpret the observed IHC pattern cautiously and verify unexpected staining with an independent approach when available (HPA tissue IHC; general IHC practice). |
Experiment evidence
IHC & IF images showing SIK2 staining
A04515-1 · IHCIHC analysis of SIK2 using anti-SIK2 antibody (A04515-1). SIK2 was detected in a paraffin-embedded section of mouse brain tissue. Heat media
A04515-1 · IHCIHC analysis of SIK2 using anti-SIK2 antibody (A04515-1). SIK2 was detected in a paraffin-embedded section of rat brain tissue. Heat mediate
A04515-1 · IFIF analysis of SIK2 using anti-SIK2 antibody (A04515-1) and anti-Beta Tubulin antibody (M01857-3). SIK2 was detected in an immunocytochemica
A04515 · IFImmunocytochemistry of SIK2 in SW480 cells with SIK2 antibody at 2.5 μg/ml.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000170145-SIK2/tissue/cerebral+cortex#imid_4271164
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000170145-SIK2/tissue/colon#imid_4271090
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000170145-SIK2/tissue/liver#imid_4271075
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000170145-SIK2/tissue/kidney#imid_4271084
HPA · ICC-IF CACO-2Human Protein Atlas immunofluorescence, CACO-2, antibody HPA071049; green = SIK2, blue = nucleus, red = microtubules.
HPA · ICC-IF CACO-2Human Protein Atlas immunofluorescence, CACO-2, antibody HPA071049; green = SIK2, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for SIK2 IHC & IF
🧪Run appendix first: glandular cells should stain for SIK2 (HPA: Medium in appendix glandular cells). Run smooth muscle as the negative tissue (HPA: Not detected in smooth muscle cells); on the appendix slide, smooth muscle cells should show little or no staining relative to the glands (HPA: Not detected in smooth muscle cells).
Positive control tissue: Adrenal gland (Glandular cells, HPA Medium)
Negative control tissue: Bone marrow (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show SIK2 in CACO-2, SiHa, U2OS, with annotated localisation: Nucleoplasm (approved), Vesicles (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control, a concentration-matched rabbit IgG isotype control matched to the primary antibody’s clonality, and SIK2-knockout tissue as a biological negative (caption: rabbit anti-SIK2 antibody; standard IHC practice). Quench endogenous peroxidase and check for staining in inflammatory cells on the appendix slide (standard chromogenic IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported in the supplied evidence, and the selected A04515-1 paraffin-section caption does not state a fixative (caption: fixative not stated). Heat retrieval in EDTA at pH 8.0 was used for the catalog antibody’s mouse brain IHC image, but whether SIK2 staining depends on that retrieval condition is unreported (caption: EDTA retrieval in mouse brain). The supplied evidence does not establish whether frozen sections or IF are easier; in appendix IHC, staining of inflammatory cells can complicate interpretation of the glandular signal (HPA: Medium in appendix glandular cells; standard chromogenic IHC practice).
HPA tissue IHC evidence for SIK2
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low consistency between antibody staining and RNA expression data.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | Medium | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Medium | Protein (IHC) | HPA → |
| Breast | Myoepithelial cells | Medium | Protein (IHC) | HPA → |
| Caudate | Neuronal cells | Medium | Protein (IHC) | HPA → |
| Cerebellum | Cells in molecular layer | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
| Lymph node | Germinal center cells | Not detected | Protein (IHC) | HPA → |
| Ovary | Follicle cells | Not detected | Protein (IHC) | HPA → |
| Smooth muscle | Smooth muscle cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced SIK2 IHC Tips
Troubleshoot SIK2 staining in paraffin sections by checking retrieval, tissue processing, cellular distribution, controls, and scoring before interpreting DAB signal.
How should I retrieve SIK2 antigen when paraffin-section staining is weak?
Start with heat-mediated antigen retrieval in EDTA, pH 8.0, for paraffin sections stained with A04515-1 (datasheet A04515-1). The reported workflow used 10% goat-serum blocking, 2 μg/ml primary antibody overnight at 4°C, and a peroxidase secondary for 30 minutes at 37°C before DAB development (datasheet A04515-1). If signal is weak, compare heating and cooling conditions on matched sections while holding antibody concentration and DAB development constant (standard IHC practice). Test another retrieval buffer only as a fallback, alongside a section processed with the original EDTA condition to assess staining and tissue preservation (standard IHC practice).
Which fixation variables could explain inconsistent SIK2 staining?
The selected paraffin-section image does not identify its fixative, so target-specific SIK2 fixation sensitivity is unknown (datasheet A04515-1). Record the fixative, fixation duration, specimen thickness, and delay before fixation, then compare sections processed together (standard IHC practice). Uneven processing can produce differences between the section edge and center; inspect morphology and the counterstain before treating those differences as SIK2 distribution (standard IHC practice). Keep retrieval at EDTA, pH 8.0 and the primary antibody at 2 μg/ml while assessing processing variation (datasheet A04515-1). Do not infer fixation tolerance from cytoplasmic tissue staining or reported protein modifications (HPA tissue IHC; UniProt Q9H0K1).
Should SIK2 appear only in the cytoplasm of stained tissue cells?
Expect substantial cytoplasmic staining in tissue sections because the tissue profile describes cytoplasmic expression in most tissues (HPA tissue IHC). SIK2 is also annotated in the cytoplasm and at the endoplasmic reticulum membrane, without a transmembrane segment (UniProt Q9H0K1). Nuclear staining merits evaluation: cell-based imaging reports nucleoplasm and vesicles as main locations, with cytosol and nuclear speckles also observed (HPA subcellular). Compare compartments within intact cells and across matched sections, using a nuclear counterstain to avoid mistaking overlapping cells or deposited DAB for nuclear signal (standard IHC practice). Treat a location as convincing only when its cellular pattern survives retrieval and detection controls (standard IHC practice).
Could an isoform or modified epitope explain discrepant SIK2 staining?
The supplied record lists 0 isoforms, so it provides no isoform-specific explanation for a staining difference (UniProt Q9H0K1). SIK2 contains a kinase domain at residues 20–271 and a UBA domain at 295–335, with modifications reported at several residues, including 175 and 534 (UniProt Q9H0K1). The selected image does not map the antibody epitope, so its relationship to these regions or modifications remains unknown (datasheet A04515-1; UniProt Q9H0K1). Compare matched sections under the reported EDTA, pH 8.0 retrieval condition before attributing a discrepancy to epitope accessibility (datasheet A04515-1; standard IHC practice).
How can I check SIK2 localisation by IF alongside chromogenic IHC?
Use IF as a separate pilot because the supplied catalog-antibody evidence describes paraffin-section IHC with DAB, while the subcellular resource reports ICC/IF images without establishing this catalog antibody’s IF performance (datasheet A04515-1; HPA subcellular). Multiplex SIK2 with a marker for the cell population being assessed; neuronal cells in cerebral cortex are one reported medium-staining IHC population (HPA tissue IHC; standard IF practice). Choose a spectrally separated fluorophore, favoring a longer wavelength when tissue autofluorescence interferes, and include single-label and secondary-only controls (standard IF practice). Permeabilize to assess intracellular and ER-associated signal, but do not assume a membrane-facing epitope because SIK2 lacks a transmembrane segment and the antibody epitope is unmapped (UniProt Q9H0K1; datasheet A04515-1; standard IF practice).
How do I reduce diffuse or granular DAB background?
First compare a no-primary section with the stained section to identify signal arising from detection reagents or tissue rather than primary-antibody binding (standard IHC practice). Apply an endogenous peroxidase block before peroxidase detection, and keep DAB development comparable across sections (standard IHC practice). The reported workflow used 10% goat serum, 2 μg/ml primary antibody overnight at 4°C, and a peroxidase secondary for 30 minutes at 37°C (datasheet A04515-1). If background persists, assess washing, primary concentration, and section integrity one variable at a time; interpret granular deposits against the expected cellular pattern (standard IHC practice; HPA tissue IHC).
What should I measure to compare SIK2 IHC across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring; tissue IHC describes predominantly cytoplasmic SIK2 expression, while cell-based imaging reports additional locations (HPA tissue IHC; HPA subcellular). For cellular staining, record the percentage of viable target cells at intensity scores 0–3 and calculate an H-score from 0–300, or report the percentage positive using a preset threshold (standard IHC scoring practice). For spatial comparisons, report positive-cell density per mm² of viable tissue or a defined compartment (standard IHC scoring practice). Normalize to the number of eligible cells or measured viable area, and hold retrieval, imaging, and DAB development constant across groups (standard IHC practice).
How can I distinguish genuine SIK2 staining from artefact?
Look for staining within intact, identifiable cells and compare its compartment with the cytoplasmic tissue profile and the reported intracellular locations (HPA tissue IHC; HPA subcellular). Medium staining in cerebral-cortex neuronal cells and undetected staining in bone-marrow hematopoietic cells provide reference observations, but the tissue resource reports low consistency between staining and RNA data (HPA tissue IHC). Discount signal concentrated at section edges, in necrotic areas, or outside cells until processing and morphology have been checked (standard IHC practice). Compare no-primary and peroxidase-block controls to assess nonspecific deposition and endogenous enzyme activity before assigning DAB signal to SIK2 (standard IHC practice).
Boster reagents
Best SIK2 / Serine/threonine-protein kinase SIK2 IHC Antibodies
Anti-SIK2 antibodies have IHC images from paraffin-embedded mouse and rat brain sections (A04515-1 IHC captions) and IF/ICC images from human cells and rat brain (catalog IF/ICC captions).
Real IHC data
Anti-SIK2 Antibody ®
Cat # A04515-1
Real IF data
Anti-SIK2 Antibody
Cat # A04515
A04515-1 has IHC images from mouse and rat brain sections and IF images from human U2OS cells and rat brain (A04515-1 image captions). A04515 has ICC and IF images from human SW480 cells (A04515 image captions).
Which to pick: Choose A04515-1 for mouse or rat paraffin-section IHC: its listed dilution is 2–5 μg/ml, and its IHC captions show EDTA retrieval at pH 8.0; the fixative is unreported (A04515-1 dilution listing and IHC captions). For human-cell IF/ICC, A04515 has SW480 images, while A04515-1 has a U2OS IF image (A04515 and A04515-1 image captions). For cross-species planning, both list human, mouse and rat reactivity, but the tissue IHC images cover mouse and rat only; clonality is unreported for both (catalog reactivity and clone fields; A04515-1 IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q9H0K1 (SIK2_HUMAN, Serine/threonine-protein kinase SIK2).
- Human Protein Atlas. SIK2 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. SIK2 subcellular location (ICC-IF): Mainly localized to the nucleoplasm and vesicles. In addition localized to the nuclear speckles, cytosol and intermediate filaments..
- Human Protein Atlas. SIK2 antibody validation summary (2 antibodies).
- SIK2 activates the autophagy‒apoptosis pathway through SP1 regulation to inhibit the progression of hepatocellular carcinoma. Frontiers in pharmacology 2025 — PMC12528092.
- SIK2 attenuates proliferation and survival of breast cancer cells with simultaneous perturbation of MAPK and PI3K/Akt pathways. Oncotarget 2018 — PMC5955149.
- SIK2 mediated mitochondrial homeostasis in spinal cord injury: modulating oxidative stress and the AIM2 inflammasome via CRTC1/CREB signaling. Journal of neuroinflammation 2025 — PMC12676768.
- Salt-Inducible Kinase 2-Triggered Release of Its Inhibitor from Hydrogel to Suppress Ovarian Cancer Metastasis. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 2022 — PMC9353504.
- PubMed PMID:14976552 — UniProt-cited evidence.
- PubMed PMID:9872452 — UniProt-cited evidence.
- PubMed PMID:12168954 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for SIK2 (Serine/threonine-protein kinase SIK2). Expected localisation Cytoplasmic tissue staining (HPA tissue IHC); ER membrane location (UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A04515-1). Validated IHC antibody: A04515-1 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative Bone marrow. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded mouse brain tissue; fixative not specified (datasheet A04515-1); 2. Fixation: Image fixative and duration unreported (datasheet A04515-1); 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 A04515-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A04515-1); 8. Primary antibody: Rabbit anti-SIK2, 2-5 μg/ml (datasheet A04515-1); 9. Primary incubation: Overnight at 4 °C (datasheet A04515-1). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Staining has low consistency with RNA expression (HPA tissue IHC); Isoform / epitope: 0 isoforms; no processing or extracellular domain (UniProt); Regulation: Low tissue specificity (HPA RNA specificity). Evidence: UniProt Q9H0K1, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the nucleoplasm and vesicles. In addition…, Datasheet A04515-1, PMC12528092, PMC5955149. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/SIK2/immunohistochemistry-ihc-guide.