CDK13 / Cyclin-dependent kinase 13 · IHC design guide

Design Immunohistochemistry for CDK13

Plan CDK13 staining in paraffin sections using the catalog antibody’s IHC protocol. Compare nuclear speckle expectations (UniProt) with tissue staining cautiously because HPA rates its IHC evidence uncertain (HPA tissue IHC).

Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use

Immunohistochemistry protocol sheet for CDK13 (IHC for CDK13): expected localisation Nuclear speckles expected; tissue compartment unverified (UniProt), antibody A05292-1, validated IHC image, and IHC protocol steps — Printable **CDK13** IHC protocol sheet — expected localisation Nuclear speckles expected; tissue compartment unverified (UniProt), antibody A05292-1, controls and protocol steps. Open the full CDK13 IHC guide →

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CDK13 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	Nuclear speckles expected; tissue compartment unverified (UniProt)
	Staining pattern	High in duodenal glandular and kidney tubular cells (HPA tissue IHC)
	Antigen retrieval	EDTA pH 8.0 HIER, heat-mediated (datasheet A05292-1)
	Positive control ⓘ	Duodenum+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 samples. (standard IHC practice; not target-specific)
	Caveat	Staining has low concordance with RNA expression (HPA tissue IHC)
	Regulation	No expression regulator specified (UniProt)
	Isoform / epitope	2 isoforms; check epitope coverage (UniProt)

Section 1

Recommended CDK13 IHC & IF Protocols

The catalog antibody uses EDTA pH 8.0 retrieval (datasheet: A05292-1). The published CDK13 IHC protocols below cover gastric cancer and glioblastoma tissue (PMC8427521; PMC13179391).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	Paraffin-embedded human esophageal squamous carcinoma tissue; fixative not specified (datasheet A05292-1)
Fixation	Image fixative and duration unreported (datasheet A05292-1); 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 A05292-1); 20 min, 95–100 °C (standard)
Peroxidase block	3% H2O2, 10 min, room temperature (standard)
Blocking	10% goat serum (datasheet A05292-1)
Primary antibody	Rabbit anti-CDK13, 2-5μg/ml (datasheet A05292-1)
Primary incubation	Overnight at 4 °C (datasheet A05292-1)
Detection	Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A05292-1)
Counterstain	Hematoxylin, blue, dehydrate and mount (standard)
Expected result	CDK13-positive staining in glandular cells of duodenum (HPA tissue IHC: High). HPA tissue profile: Expression in several tissues. No signal in the no-primary control.

💡Decision noteStart with heat-mediated EDTA pH 8.0 for the catalog antibody (datasheet: A05292-1); consider the published low-pH retrieval for glioblastoma sections (PMC13179391: methods).

Section 2

What Is the Expected CDK13 Staining Pattern?

CDK13 is expected mainly in nuclear speckles (UniProt Q14004; HPA: nuclear speckles supported). In paraffin IHC, look for predominantly nuclear staining in duodenal glandular cells and kidney tubular cells, both reported as high (HPA: tissue IHC). Interpret intensity cautiously: HPA rates the tissue IHC pattern uncertain because antibody staining has low consistency with RNA expression (HPA: tissue IHC reliability). CDK13 has no transmembrane segment (UniProt Q14004 topology).

What am I looking at on my slide?
Predominantly nuclear staining in duodenal glandular cells or kidney tubular cells, possibly speckled where detail is resolved.	This fits the reported high staining in those cell types (HPA: tissue IHC) and the nuclear speckle location (UniProt Q14004; HPA: ICC-IF supported). Chromogenic IHC may show a nuclear signal without resolving individual speckles (general IHC practice). Score the relevant cells and compartment rather than treating all staining across a section as equivalent.
Strong, broadly cytoplasmic staining with little nuclear staining.	Treat this as a questionable CDK13 pattern and check controls, retrieval and detection background (general IHC practice). Nuclear speckles are the supported location; Golgi apparatus and cytosol are additional uncertain locations in ICC-IF (HPA: subcellular). A cytoplasmic signal alone therefore does not establish specific CDK13 staining, but it is not proof of an artefact.
Strong staining in an unexpected cell population, especially alongside weak staining in the chosen positive cells.	Compare the exact cell type before assigning a result: HPA reports high staining in kidney tubular cells but no detection in bone marrow hematopoietic cells (HPA: tissue IHC). An unexpected pattern may reflect cross-reactivity or endogenous detection activity (general IHC practice); it cannot be resolved from tissue identity alone because HPA rates CDK13 tissue IHC uncertain (HPA: reliability).
Diffuse color across nuclei, cytoplasm and extracellular areas, including areas without expected positive cells.	This limits compartment and cell-type scoring and suggests background from the staining workflow (general IHC practice). Review the reagent-omission control, blocking, washes and detection chemistry (general IHC practice). The reported CDK13 pattern is mainly nuclear speckles (UniProt Q14004; HPA: subcellular), while the tissue IHC evidence remains uncertain (HPA: reliability).
No convincing signal in duodenal glandular cells or kidney tubular cells.	These are useful positive-reference cell populations because HPA reports high IHC staining in each (HPA: tissue IHC). First check whether the relevant cells are present and whether the run's positive control stained; then review retrieval, antibody dilution and detection steps (general IHC practice). Absence in one specimen alone does not settle CDK13 expression, given the uncertain HPA tissue IHC reliability (HPA: reliability).

💡Expected CDK13 appearanceCall a plausible positive result predominantly nuclear staining in duodenal glandular or kidney tubular cells, with potentially resolvable speckles and comparatively strong signal (HPA: tissue IHC high; HPA: nuclear speckles supported); diffuse section-wide color or isolated strong cytoplasmic signal warrants control review (general IHC practice; HPA: additional cytosol uncertain).

How each factor affects the staining
Subcellular location	Nuclear speckles are supported by ICC-IF and listed by UniProt (HPA: subcellular; UniProt Q14004). Golgi apparatus and cytosol are uncertain additional ICC-IF locations (HPA: subcellular). Use nuclear enrichment as the principal localization check in IHC; do not require individually visible speckles in a chromogenic section (general IHC practice).
Tissue pattern and evidence strength	HPA reports high staining in duodenal glandular, kidney tubular, small-intestinal glandular and seminiferous-duct cells (HPA: tissue IHC). Its overall tissue IHC reliability is uncertain because staining and RNA data have low consistency (HPA: reliability). Treat these as observed reference patterns rather than definitive proof of specificity in every specimen.
Protein architecture and isoforms	CDK13 is a 1,512-residue protein with no signal peptide, propeptide or transmembrane segment; UniProt lists two isoforms and a kinase domain at residues 705–998 (UniProt Q14004). These facts support a nonmembrane localization expectation, but they do not identify the catalog antibody's epitope or predict retrieval performance (UniProt Q14004).
IF/ICC: what localization should be expected?	Mainly nuclear speckles, supported in HPA ICC-IF and consistent with UniProt; Golgi apparatus and cytosol are additional uncertain locations (HPA: subcellular; UniProt Q14004). HPA lists HeLa, SiHa, U2OS and KOLF2.1J among cell lines with ICC-IF images (HPA: subcellular). This localization evidence informs interpretation here; IF/ICC methods belong on the separate guide page.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Positive-reference tissue stains weakly or not at all.	The selected section may lack the relevant cells, or the IHC run may have a workflow failure (general IHC practice). HPA reports high staining in duodenal glandular and kidney tubular cells, with uncertain overall reliability (HPA: tissue IHC).	Confirm the reference cells are present, review the run's positive control, then check retrieval, catalog antibody dilution and detection according to the validated IHC procedure (general IHC practice). Avoid declaring a biological negative from one failed section.
Staining is predominantly cytoplasmic.	The signal conflicts with the supported nuclear-speckle localization, although cytosol is an uncertain additional ICC-IF location (HPA: subcellular). Background or nonspecific binding is possible (general IHC practice).	Compare nuclear and cytoplasmic signal in the expected positive cells, examine reagent-omission controls, and repeat with the validated IHC conditions if controls are unsatisfactory (general IHC practice; HPA: tissue IHC high in duodenal glandular and kidney tubular cells).
Strong signal appears in cells reported as not detected.	Cross-reactivity or endogenous detection activity is possible (general IHC practice); HPA's tissue IHC reliability is uncertain, so a discrepancy alone does not identify the cause (HPA: reliability).	Verify the cell identity and compare an expected positive cell population in the same run; inspect reagent-omission controls and detection blocking (general IHC practice). For example, HPA reports bone marrow hematopoietic cells as not detected (HPA: tissue IHC).
Diffuse chromogen obscures nuclei and tissue boundaries.	Excess background can prevent compartment scoring (general IHC practice), while the expected main CDK13 location is nuclear speckles (UniProt Q14004; HPA: subcellular).	Check reagent-omission controls, blocking, wash steps, detection exposure and antibody dilution against the validated IHC procedure (general IHC practice). Reassess only where individual cells and nuclei remain interpretable.
Different tissues give inconsistent intensity.	HPA reports several high, medium, low and not-detected cell-type patterns, and rates the overall tissue IHC evidence uncertain because staining and RNA data have low consistency (HPA: tissue IHC reliability).	Record the specific cell type, compartment and intensity for each specimen; compare expected positive and negative-reference cells in the same run before inferring a biological difference (general IHC practice; HPA: tissue IHC).
A nuclear signal is visible, but distinct speckles cannot be resolved.	Chromogenic paraffin IHC may lack the spatial detail of ICC-IF for fine intranuclear structures (general IHC practice). Nuclear speckles are the supported ICC-IF location (HPA: subcellular).	Judge whether staining is predominantly nuclear in the expected cells and whether controls are acceptable (HPA: tissue IHC high in duodenal glandular and kidney tubular cells; general IHC practice). Use the separate IF/ICC guide if speckle resolution is required.

Source: UniProt Q14004 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing CDK13 staining

IHC analysis of CDK13 using anti-CDK13 antibody (A05292-1). CDK13 was detected in paraffin-embedded section of human esophageal squamous carcinoma tissue. Heat mediated antigen retrieval was performed in EDTA buffer (pH8.0, epitope retrieval solution). The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 2μg/ml rabbit anti-CDK13 Antibody (A05292-1) overnight at 4°C. Biotinylated goat anti-rabbit IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC) (Catalog # SA1022) with DAB as the chromogen.

A05292-1 · IHCIHC analysis of CDK13 using anti-CDK13 antibody (A05292-1). CDK13 was detected in paraffin-embedded section of human esophageal squamous car

IF analysis of CDK13 using anti-CDK13 antibody (A05292-1). CDK13 was detected in immunocytochemical section of HELA cells. Enzyme antigen retrieval was performed using IHC enzyme antigen retrieval reagent (AR0022) for 15 mins. The cells were blocked with 10% goat serum. And then incubated with 5μg/mL rabbit anti-CDK13 Antibody (A05292-1) overnight at 4°C. DyLight®594 Conjugated Goat Anti-Rabbit IgG (BA1142) was used as secondary antibody at 1:100 dilution and incubated for 30 minutes at 37°C. The section was counterstained with DAPI. Visualize using a fluorescence microscope and filter sets appropriate for the label used.

A05292-1 · IFIF analysis of CDK13 using anti-CDK13 antibody (A05292-1). CDK13 was detected in immunocytochemical section of HELA cells. Enzyme antigen re

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000065883-CDK13/tissue/cerebral+cortex#imid_16418887

HPA · DuodenumHuman Protein Atlas IHC, Duodenum. Source: https://www.proteinatlas.org/ENSG00000065883-CDK13/tissue/duodenum#imid_16418796

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000065883-CDK13/tissue/colon#imid_16418813

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000065883-CDK13/tissue/liver#imid_16418806

HPA · ICC-IF HeLaHuman Protein Atlas immunofluorescence, HeLa, antibody HPA059241; green = CDK13, blue = nucleus, red = microtubules.

← swipe / scroll for more images →

Real IHC / IF data behind the staining-pattern expectations in this section.

Sample controls for CDK13 IHC & IF

🧪Run duodenum first and score its glandular cells for CDK13 staining (HPA: High in duodenal glandular cells). Use adipose tissue adipocytes as the negative tissue (HPA: Not detected in adipocytes); on the duodenal slide, treat unstained cells outside the glandular compartment as a background reference only after confirming their identity, since the supplied HPA row does not classify them.

Positive control tissue: Duodenum (Glandular cells, HPA High)

Negative control tissue: Adipose tissue (HPA Not detected)

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CDK13 in HeLa, SiHa, U2OS, KOLF2.1J, with annotated localisation: Nuclear speckles (supported) (HPA subcellular).

Technical controls: Include a no-primary, secondary-only slide, a concentration-matched rabbit isotype control for the rabbit catalog antibody, and CDK13-knockout material as a biological negative (selected-SKU caption: rabbit anti-CDK13 antibody). Block endogenous peroxidase and assess endogenous biotin background when using the caption’s biotin–SABC/DAB detection in duodenum (selected-SKU caption: biotinylated secondary, SABC and DAB; HPA: duodenum).

⚠️Feasibility: No target-specific fixation window or fixation effect is reported, and the selected-SKU paraffin-section caption does not state a fixative (selected-SKU caption: fixative not stated). The caption uses heat-mediated EDTA retrieval at pH 8.0, but does not establish that CDK13 staining depends on that retrieval condition (selected-SKU caption: EDTA retrieval, pH 8.0). Whether frozen sections or IF are easier is unreported; for IF, nuclear speckles are the supported localization, while Golgi and cytosolic signals are uncertain (HPA: subcellular localization).

HPA tissue IHC evidence for CDK13

Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Uncertain — Low consistency between antibody staining and RNA expression data. Pending external verification.). 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
Duodenum	Glandular cells	High	Protein (IHC)	HPA →
Kidney	Cells in tubules	High	Protein (IHC)	HPA →
Small intestine	Glandular cells	High	Protein (IHC)	HPA →
Testis	Cells in seminiferous ducts	High	Protein (IHC)	HPA →
Fallopian tube	Glandular cells	Medium	Protein (IHC)	HPA →

Undetected expression · recommended negative controls

Tissue	Cell type	Level	Evidence	Source
Adipose tissue	Adipocytes	Not detected	Protein (IHC)	HPA →
Adrenal gland	Glandular cells	Not detected	Protein (IHC)	HPA →
Bone marrow	Hematopoietic cells	Not detected	Protein (IHC)	HPA →
Breast	Adipocytes	Not detected	Protein (IHC)	HPA →
Caudate	Glial cells	Not detected	Protein (IHC)	HPA →

Section 3

Advanced CDK13 IHC Tips

Troubleshoot chromogenic CDK13 IHC in paraffin sections by checking retrieval, nuclear localisation, tissue controls and staining quality before scoring.

Which retrieval conditions should I try first for CDK13 in paraffin sections?

Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A05292-1). The selected tissue image used this retrieval before overnight incubation at 4°C with 2 µg/ml primary antibody (caption A05292-1). If staining is weak, first check that heating, cooling and section adherence were consistent across slides (standard IHC practice). Compare any alternative retrieval condition on adjacent sections while keeping antibody concentration and detection constant (standard IHC practice). Judge improvement by clearer nuclear staining with restrained background, because CDK13 is mainly associated with nuclear speckles (UniProt Q14004; HPA subcellular).

How should I investigate weak CDK13 staining when fixation varies between specimens?

The selected image identifies paraffin sections but does not report the fixative, so target-specific CDK13 fixation sensitivity is unknown (caption A05292-1). Record each specimen’s fixative and fixation duration, then compare sections processed with the same retrieval and detection conditions (standard IHC practice). Include a reference section in each run to distinguish a specimen issue from run-wide staining failure (standard IHC practice). Examine tissue preservation and nuclear morphology before interpreting a faint signal, because damaged or poorly preserved areas can distort chromogenic scoring (standard IHC practice). Keep the reported EDTA pH 8.0 retrieval as the starting condition during this comparison (datasheet A05292-1).

What staining pattern should I expect, and how should I assess cytoplasmic signal?

Expect predominantly nuclear CDK13 staining, consistent with its reported nuclear-speckle localisation (UniProt Q14004; HPA subcellular). Assess whether signal lies within intact nuclei on the counterstained section, since DAB deposits alone cannot resolve individual speckles reliably (standard IHC practice). The HPA also reports Golgi and cytosolic localisation with uncertain support, so cytoplasmic staining needs independent confirmation before it is scored as CDK13 (HPA subcellular). CDK13 has no transmembrane segment, making a crisp membrane-only pattern especially suspect (UniProt Q14004 topology). Compare the suspect area with a no-primary control and a reference section stained in the same run (standard IHC practice).

Could isoforms or epitope accessibility explain discordant CDK13 staining?

CDK13 has 2 listed isoforms, and its kinase domain spans residues 705–998 (UniProt Q14004). The supplied antibody caption does not identify its epitope, so isoform recognition and sensitivity to nearby modifications cannot be assigned to this antibody (caption A05292-1). CDK13 includes reported phosphoserines at residues 315, 317, 325, 340 and 342, but those sites alone do not establish an IHC staining effect (UniProt Q14004). If samples disagree, compare the antibody’s documented immunogen with isoform sequences when that information becomes available (standard IHC validation practice). Meanwhile, assess retrieval and tissue quality on matched sections before attributing discordance to an isoform (standard IHC practice).

How can IF help evaluate an uncertain CDK13 IHC pattern?

Use IF as a separate confirmation experiment, since the selected antibody evidence describes chromogenic staining of paraffin tissue rather than an IF protocol (caption A05292-1). Multiplex CDK13 with a validated marker of the expected cell type, such as glandular cells when examining duodenum, to identify which cells carry the signal (HPA tissue; standard IF practice). Choose spectrally separated fluorophores and consider a longer-wavelength channel if tissue autofluorescence obscures shorter-wavelength signal (standard IF practice). Because the expected CDK13 signal is nuclear and CDK13 has no transmembrane segment, permeabilise sufficiently for nuclear antibody access (UniProt Q14004; standard IF practice). Check nuclear-speckle enrichment against a no-primary control (HPA subcellular; standard IF practice).

How do I reduce diffuse or granular DAB background without losing nuclear signal?

First compare a no-primary control with the stained section to locate background arising from secondary detection or tissue components (standard IHC practice). The selected image used 10% goat serum blocking, a biotinylated goat anti-rabbit secondary and a streptavidin–biotin complex with DAB (caption A05292-1). If background follows this detection system, assess endogenous biotin and endogenous peroxidase controls alongside the routine peroxidase block (standard IHC practice). Reduce excessive primary exposure only after checking blocking, washes and detection controls, then reassess nuclear contrast (standard IHC practice). Keep tissue edges and damaged regions out of the assessment when their staining differs from preserved interior tissue (standard IHC practice).

How should I score CDK13 IHC across tissues with different cell compositions? ⚠ ANSWER MARKED FOR VERIFICATION

Define the cell population and compartment before scoring; nuclear staining is the principal CDK13 readout (UniProt Q14004; HPA subcellular). For a consistent population, report the percentage of positive nuclei and, if intensity is reproducible, an H-score from 0–300 (standard IHC scoring practice). Where mixed cell populations make proportions misleading, report positive-cell density per mm² of viable tissue or score each annotated population separately (standard IHC scoring practice). Normalise counts to the corresponding eligible nuclei or viable tissue area, using the same thresholds and exclusions across slides (standard IHC scoring practice). Record run controls and avoid treating HPA tissue levels as calibration standards because its tissue staining reliability is uncertain (HPA tissue).

How can I distinguish credible CDK13 positivity from staining artefact?

A credible result shows reproducible staining in intact nuclei, matching CDK13’s principal nuclear-speckle localisation (UniProt Q14004; HPA subcellular). Check cell identity: HPA reports high staining in duodenal glandular cells and kidney tubular cells, while its overall tissue-IHC reliability is uncertain (HPA tissue). Treat isolated membrane-only signal, edge accentuation and staining confined to necrotic areas as reasons for closer control review (UniProt Q14004 topology; standard IHC practice). Compare no-primary and peroxidase-control sections to detect background from the detection system or endogenous enzyme activity (standard IHC practice). Resolve disputed positivity with repeat sections and an independently validated antibody where available (standard IHC validation practice).

Boster reagents

Best CDK13 / Cyclin-dependent kinase 13 IHC Antibodies

A05292-1 has human paraffin-section IHC data from esophageal squamous carcinoma and IF/ICC data from HELA cells (catalog image captions; catalog applications/reactivity).

Real IHC data

Anti-CDK13 Antibody ®

Cat # A05292-1

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A05292-1 was demonstrated by chromogenic IHC on a paraffin-embedded human esophageal squamous carcinoma section (catalog IHC image caption). The same SKU was demonstrated by IF/ICC on HELA cells (catalog IF image caption).

Which to pick: Choose A05292-1 for human paraffin-section IHC; its IHC image used 2 μg/ml, EDTA retrieval at pH 8.0, and DAB detection (catalog IHC image caption). Choose A05292-1 for IF/ICC on HELA cells; its IF image used 5 μg/ml and a fluorescent secondary antibody (catalog IF image caption). Cross-species reactivity is unreported (catalog reactivity: Human only), and the paraffin-section IHC caption does not report the fixative (catalog IHC image caption).

Each figure is that product's own IHC / IF validation image from its datasheet.

References

UniProt Consortium. UniProt entry Q14004 (CDK13_HUMAN, Cyclin-dependent kinase 13).
Human Protein Atlas. CDK13 tissue IHC expression (reliability: Uncertain).
Human Protein Atlas. CDK13 subcellular location (ICC-IF): Mainly localized to the nuclear speckles. In addition localized to the Golgi apparatus and cytosol..
Human Protein Atlas. CDK13 antibody validation summary (1 antibodies).
CDK13-Mediated Cell Cycle Disorder Promotes Tumorigenesis of High HMGA2 Expression Gastric Cancer. Frontiers in molecular biosciences 2021 — PMC8427521.
CDK12/CDK13 inhibition disrupts transcriptional elongation and replication fork progression in glioblastoma. EMBO molecular medicine 2026 — PMC13179391.
CDK13 drives clear cell renal carcinoma through METTL16-mediated m(6)A modification of ACLY mRNA. Experimental & molecular medicine 2026 — PMC12992896.
CDK13 upregulation-induced formation of the positive feedback loop among circCDK13, miR-212-5p/miR-449a and E2F5 contributes to prostate carcinogenesis. Journal of experimental & clinical cancer research : CR 2021 — PMC7780414.
PubMed PMID:11162436 — UniProt-cited evidence.
PubMed PMID:12853948 — UniProt-cited evidence.
PubMed PMID:1731328 — UniProt-cited evidence.