CDK13 / Cyclin-dependent kinase 13 · IHC design guide

Design Immunohistochemistry for CDK13

Plan chromogenic CDK13 IHC in paraffin sections with catalog antibody A05292-1 at 2–5 μg/mL (datasheet), using duodenal glandular cells or kidney tubules as high-staining references (HPA tissue IHC). Nuclear speckles are the molecular expectation (UniProt), while the tissue staining evidence has uncertain reliability (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 are the molecular expectation (UniProt), antibody A05292-1, validated IHC image, and IHC protocol steps — Printable **CDK13** IHC protocol sheet — expected localisation Nuclear speckles are the molecular expectation (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 are the molecular expectation (UniProt)
	Staining pattern	High staining in glandular and tubular cells; compartment unreported (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 sections. (standard IHC practice; not target-specific)
	Caveat	Staining–RNA agreement is low; tissue reliability is uncertain (HPA tissue IHC)
	Regulation	Fetal brain, liver and muscle; adult brain (UniProt)
	Isoform / epitope	2 isoforms; epitope differences are unreported (UniProt)

Section 1

Recommended CDK13 IHC & IF Protocols

The catalog antibody’s IHC-P protocol is paired with published CDK13 IHC methods for gastric cancer and glioblastoma (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 at pH 8.0 for the catalog antibody (datasheet: A05292-1); the glioblastoma protocol used low-pH retrieval (PMC13179391).

Section 2

What Is the Expected CDK13 Staining Pattern?

CDK13 is a nuclear speckle protein (UniProt Q14004; HPA subcellular: supported). In paraffin section IHC, expect staining chiefly in cells reported as positive by HPA, especially duodenal and small intestinal glandular cells, kidney tubular cells, and cells in testicular seminiferous ducts (HPA tissue IHC: High). Treat tissue predictions cautiously: HPA rates its CDK13 tissue IHC reliability Uncertain because antibody staining and RNA expression have low consistency (HPA tissue IHC: Uncertain).

What am I looking at on my slide?
Staining is concentrated over nuclei in the expected cell population.	This fits CDK13's nuclear speckle localization (UniProt Q14004; HPA subcellular: supported). In chromogenic IHC, fine speckles may be difficult to resolve; judge nuclear enrichment alongside the cell distribution (general IHC interpretation). HPA reports High staining in duodenal and small intestinal glandular cells, kidney tubular cells, and cells in seminiferous ducts (HPA tissue IHC: High).
Strong staining is mainly cytoplasmic, membranous, or outside nuclei.	A dominant nonnuclear IHC pattern conflicts with the supported nuclear speckle location (UniProt Q14004; HPA subcellular: supported). Review tissue morphology, counterstain, and detection controls before interpreting it as CDK13 (general IHC practice). HPA also reports Golgi and cytosolic IF signals, but marks both additional locations Uncertain (HPA subcellular: uncertain).
Strong signal appears in cells reported as not detected, such as adipocytes or bone marrow hematopoietic cells.	That distribution differs from the sampled HPA tissue IHC observations (HPA tissue IHC: Not detected in those cells). Check for cross-reactivity and endogenous detection activity with suitable controls (general IHC practice). A discordant cell type alone cannot establish the cause, particularly because HPA rates the tissue IHC profile Uncertain (HPA tissue IHC: Uncertain).
Color is diffuse across cells, stroma, or the whole section without clear nuclear enrichment.	Diffuse signal is hard to assign to the supported nuclear speckle location (UniProt Q14004; HPA subcellular: supported). Inspect a no-primary control and assess blocking, washing, chromogen development, and section quality (general IHC practice). Do not score widespread haze as positive solely because the tissue appears on HPA's positive list (HPA tissue IHC: Uncertain).
No signal is seen in a tissue and cell population listed as High.	First confirm that the expected cells are present and preserved, then review the IHC-validated antibody's specified procedure and detection controls (general IHC practice). An absent signal disagrees with the reported High observation but does not by itself prove assay failure or biological absence: HPA describes the tissue IHC evidence as Uncertain (HPA tissue IHC: High; Uncertain).

💡Expected CDK13 appearanceCall a section positive when staining is predominantly nuclear in HPA-reported positive cells, with the strongest expected examples being glandular cells in duodenum or small intestine, kidney tubular cells, and cells in seminiferous ducts (UniProt Q14004; HPA subcellular: supported; HPA tissue IHC: High); isolated strong nonnuclear staining or uniform background warrants control review (general IHC interpretation).

How each factor affects the staining
Tissue and cell selection	HPA reports High staining in four listed cell populations, Medium staining in fallopian tube, oral mucosa, rectum, and stomach cells, and Low staining in several others (HPA tissue IHC). Use the stated cell type within each tissue when interpreting a section; a tissue name alone is too broad. The overall tissue IHC reliability remains Uncertain (HPA tissue IHC: Uncertain).
Subcellular readout and IF/ICC Q&A	What should IF/ICC show? Mainly nuclear speckles (HPA subcellular: supported; UniProt Q14004). HPA reports additional Golgi and cytosolic localization as Uncertain, so those signals should not displace nuclear localization as the principal expectation (HPA subcellular). This IF/ICC observation informs compartment interpretation; this section provides no IF/ICC protocol.
Antibody evidence	The listed antibody HPA059241 has IHC status Uncertain and ICC status Supported (HPA antibodies). Agreement between a chromogenic pattern and the nuclear localization is useful, but the IHC validation status does not establish every stained tissue or cell as a confirmed CDK13 positive (HPA antibodies; HPA tissue IHC: Uncertain).
Target features	CDK13 has no reported transmembrane segment or signal peptide and has two listed isoforms (UniProt Q14004 topology; isoforms). Those facts are consistent with interpreting nuclear staining and give no basis to expect a surface or secreted staining pattern. The supplied record gives no antibody epitope, so isoform-specific staining cannot be predicted from it.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Expected nuclei are faint or blank in a reported High cell population.	Possible assay or detection failure, or variation in the observed tissue pattern; HPA rates its CDK13 tissue IHC Uncertain (HPA tissue IHC).	Verify the expected cells and section quality, then check the catalog antibody's IHC-P instructions, detection reagents, and a positive control (general IHC practice). Interpret absence against the HPA uncertainty rather than declaring CDK13 absent.
Chromogen covers the section or obscures nuclear detail.	Nonspecific background or excessive development can prevent compartment assessment (general IHC practice).	Compare a no-primary control, inspect washing and blocking, and adjust development according to the assay instructions (general IHC practice). Score only interpretable cell-associated staining.
Signal is strongest in cytoplasm or along cell borders.	The dominant location conflicts with supported nuclear speckles (UniProt Q14004; HPA subcellular: supported); the cause remains undetermined.	Recheck morphology and controls, and reassess the antibody and detection system (general IHC practice). Treat Golgi or cytosolic IF localization cautiously because HPA labels it Uncertain (HPA subcellular).
Adipocytes or bone marrow hematopoietic cells stain strongly.	Those cells are listed as Not detected in the sampled HPA tissue IHC images (HPA tissue IHC); cross-reactivity or endogenous detection activity is possible (general IHC practice).	Compare the no-primary control and expected positive cells, then verify cell identity and staining distribution before assigning the signal to CDK13 (general IHC practice).
A reported Low tissue shows little or no visible staining.	HPA reports Low staining in specific cells of bronchus, esophagus, placenta, heart muscle, appendix, and tonsil (HPA tissue IHC).	Check the stated cell population and use a reported High population for assay assessment (HPA tissue IHC). Avoid treating a weak Low category as a reliable negative control, given HPA's Uncertain tissue IHC rating.
Fine nuclear speckles are not individually resolved in chromogenic IHC.	Chromogenic section resolution and nuclear counterstain can limit recognition of small subnuclear structures (general IHC interpretation).	Assess nuclear enrichment and the expected cell distribution at appropriate magnification (general IHC practice; HPA tissue IHC). Use the supported speckle localization as context, without requiring visible dots in every positive nucleus (HPA subcellular: supported).

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 kidney first: cells in tubules should stain (HPA: High in kidney tubules). Use adipose tissue as the negative tissue; adipocytes should show no specific staining (HPA: Not detected in adipocytes). On the kidney slide, any cells without CDK13 signal should retain the counterstain but lack discrete nuclear speckle staining (HPA: supported nuclear speckle localization).

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 control and a concentration-matched rabbit isotype control (caption: rabbit anti-CDK13 antibody; standard IHC practice). Use CDK13 knockout tissue or cells as a biological negative where available (standard IHC practice). For kidney, quench endogenous peroxidase and check for endogenous biotin if using the caption’s biotin-based SABC/DAB detection (caption: biotinylated secondary and SABC/DAB; standard IHC practice).

⚠️Feasibility: The selected antibody caption reports heat retrieval in EDTA at pH 8.0 for a paraffin section, but its fixative is unreported; no target-specific fixation window or fixation effect is supplied (caption: retrieval and fixative not stated). The evidence does not establish whether frozen sections or IF are easier; ICC-IF images support nuclear speckles as the main location (HPA: supported nuclear speckles). In kidney tubules, endogenous biotin can complicate interpretation with the caption’s biotin-based detection system (caption: SABC/DAB; standard IHC practice).

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 CDK13 staining in paraffin sections by checking retrieval, nuclear localisation, controls and scoring before interpreting signal intensity.

How should I adjust retrieval when CDK13 staining is weak in paraffin sections?

Start with heat-mediated retrieval in EDTA at pH 8.0 (datasheet A05292-1). The selected paraffin-section example used that condition before overnight incubation with 2 µg/ml antibody at 4°C (datasheet A05292-1). If nuclear staining remains weak, compare a longer heating or cooling interval on matched sections while keeping detection conditions fixed (standard IHC practice). Include a tissue with previously observed staining, such as kidney tubules, but treat its expected signal cautiously because tissue-IHC reliability is uncertain (HPA: kidney tubules High; HPA: tissue-IHC reliability Uncertain). Check morphology alongside signal: excessive heating can damage sections and complicate nuclear scoring (standard IHC practice).

Could fixation explain weak or uneven CDK13 IHC staining?

Target-specific CDK13 fixation sensitivity is unknown: the selected paraffin-section caption does not report its fixative (datasheet A05292-1). Record the actual fixative, fixation duration and processing history for each specimen before comparing staining across blocks (standard IHC practice). When weak signal tracks with a processing batch, stain matched sections together and inspect tissue preservation before changing retrieval or antibody concentration (standard IHC practice). Use the reported EDTA pH 8.0 retrieval as the starting condition, then vary one processing or staining factor at a time (datasheet A05292-1; standard IHC practice). Nuclear speckle localisation provides a pattern to assess, but does not establish fixation tolerance (UniProt Q14004: nucleus speckle).

Which cellular pattern supports a credible CDK13 IHC result?

Prioritise nuclear staining with a speckled distribution when section resolution permits, since CDK13 is assigned to nuclear speckles (UniProt Q14004: subcellular location; HPA: nuclear speckles supported). Compare signal with a nuclear counterstain and score the intended cell population separately from neighbouring cells (standard IHC practice). Golgi and cytosolic locations have uncertain support, so predominantly extranuclear DAB staining needs additional validation before interpretation (HPA: additional locations uncertain). CDK13 has no transmembrane segment, making an isolated membrane-rim pattern discordant with its recorded topology (UniProt Q14004: topology). Confirm any unexpected pattern with an appropriate negative control and, where feasible, an independent antibody targeting another epitope (standard IHC practice).

How might CDK13 isoforms or epitope accessibility affect IHC staining?

CDK13 has 2 recorded isoforms, but the selected caption does not identify the antibody epitope or establish isoform coverage (UniProt Q14004: isoforms; datasheet A05292-1). Check the antibody's documented immunogen against both isoform sequences before assigning an isoform-specific staining pattern (standard IHC practice). The kinase domain spans residues 705–998, and recorded phosphorylation includes serines 315 and 317; neither fact alone establishes antibody sensitivity to modification (UniProt Q14004: domain and modified residues). If retrieval changes the nuclear pattern, assess epitope exposure with matched sections and controls rather than inferring altered CDK13 abundance (standard IHC practice). Report the antibody and retrieval condition with any claimed isoform comparison (standard IHC practice).

How should I follow up a CDK13 IHC pattern with multiplex IF?

Treat IF as a separate assay: the selected antibody evidence describes chromogenic staining in paraffin sections, without an IF fixation or permeabilisation condition (datasheet A05292-1). Pair CDK13 with a validated marker for the cell population being examined, plus a nuclear stain, to test cell identity and speckle localisation (UniProt Q14004: nucleus speckle; standard IF practice). Choose spectrally separated fluorophores and favour a red or far-red channel if tissue autofluorescence obscures shorter wavelengths (standard IF practice). Because CDK13 has no transmembrane segment and is mainly nuclear, permeabilisation must allow antibody access to an intracellular epitope; optimise its strength against morphology (UniProt Q14004: topology and localisation; standard IF practice).

What controls help distinguish CDK13 signal from chromogenic background?

Run a no-primary control through the same secondary antibody and DAB steps to reveal detection-system or tissue background (standard IHC practice). Apply a peroxidase block before chromogenic detection and compare its effect on problematic areas using matched sections (standard IHC practice). The selected example used a biotinylated secondary antibody, streptavidin–biotin detection and DAB, so investigate background associated with that detection sequence if diffuse staining persists (datasheet A05292-1; standard IHC practice). Keep incubation and wash conditions consistent when comparing the reported 2 µg/ml overnight primary condition with an adjusted concentration (datasheet A05292-1; standard IHC practice). Review nuclear counterstaining and tissue edges before calling faint brown deposits positive (standard IHC practice).

How should I quantify CDK13 staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION

Define the scored cell population and nuclear compartment before measuring CDK13, consistent with its supported speckle localisation (HPA: nuclear speckles supported; standard IHC practice). Report either the percentage of positive nuclei or an H-score combining staining intensity and percentage, with a possible range of 0–300 (standard IHC practice). Normalise positive counts to the number of evaluable nuclei in the same annotated region; use area in mm² if reporting positive-cell density (standard IHC practice). Apply one threshold, counterstain criterion and exclusion rule across all slides, and exclude damaged or necrotic areas (standard IHC practice). Record cell type because HPA reports differing staining levels among tissues (HPA: tissue IHC profile).

When is apparent CDK13 positivity likely to be an artefact?

A credible result should include nuclear signal in evaluable cells, consistent with CDK13 nuclear speckles (UniProt Q14004: subcellular location; HPA: nuclear speckles supported). Treat isolated membrane-rim staining cautiously because CDK13 has no transmembrane segment, and assess unexpected cell populations against matched controls (UniProt Q14004: topology; standard IHC practice). Staining confined to section edges, necrotic regions or a no-primary control suggests a processing or detection artefact (standard IHC practice). Check endogenous peroxidase background before interpreting DAB deposits as antigen signal (standard IHC practice). Tissue-IHC findings also need independent support because HPA rates antibody staining versus RNA expression consistency as uncertain (HPA: tissue-IHC reliability Uncertain).

Boster reagents

Best CDK13 / Cyclin-dependent kinase 13 IHC Antibodies

The IHC-validated antibody A05292-1 has IHC data from a human paraffin tissue section and IF/ICC data from human HeLa cells (catalog image captions; catalog reactivity: Human).

Real IHC data

Anti-CDK13 Antibody ®

Cat # A05292-1

View product →

A05292-1 was used for IHC on a paraffin-embedded human esophageal squamous carcinoma section (IHC image caption). The same SKU was used for IF/ICC on HeLa cells (IF image caption; catalog applications: IF, ICC).

Which to pick: Choose A05292-1 for tissue IHC: its image documents a paraffin section with EDTA retrieval and 2 μg/ml primary antibody; the fixative is unreported (IHC image caption). For IF/ICC, the same SKU has a HeLa cell image using 5 μg/ml primary antibody (IF image caption). No cross-species choice is supported because its listed reactivity is Human, and its clone status is unreported.

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.