CCAR2 / Cell cycle and apoptosis regulator protein 2 · IHC design guide

Design Immunohistochemistry for CCAR2

Plan CCAR2 staining in paraffin sections using the ubiquitous nuclear tissue pattern as a reference (HPA tissue IHC). This guide covers fixation consistency, controls, chromogenic detection, and scoring.

Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
Immunohistochemistry protocol sheet for CCAR2 (IHC for CCAR2): expected localisation Nuclear staining across tissues (HPA tissue IHC), antibody A03412-1, validated IHC image, and IHC protocol steps
Printable CCAR2 IHC protocol sheet — expected localisation Nuclear staining across tissues (HPA tissue IHC), antibody A03412-1, controls and protocol steps. Open the full CCAR2 IHC guide →

CCAR2 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 staining across tissues (HPA tissue IHC)
Staining pattern Widespread nuclear staining across cell types (HPA tissue IHC)
Antigen retrieval EDTA pH 8.0 HIER, heat-mediated (datasheet A03412-1)
Positive control ⓘ Bronchus+4 more · see all
Negative control ⓘ Lung
Important caveats
Reasons your staining may differ from the expected pattern.
Fixation Keep fixation consistent across sections (standard IHC practice; not target-specific)
Caveat UV-induced apoptosis may shift CCAR2 to cytoplasm (UniProt)
Regulation Rises with gastric carcinoma progression (UniProt)
Isoform / epitope 2 isoforms; check antibody epitope coverage (UniProt)
Section 1

Recommended CCAR2 IHC & IF Protocols

The catalog antibody’s IHC-P protocol is followed by three published CCAR2 staining protocols (datasheet A03412-1; PMC13229996; PMC4335761; PMC5787426).

Recommended immunohistochemistry (IHC-P) protocol parameters
SampleParaffin-embedded human gall bladder adenosquamous carcinoma tissue; fixative not specified (datasheet A03412-1)
FixationImage fixative and duration unreported (datasheet A03412-1); verify before use.
Sectioning4–5 µm sections on charged slides (standard)
DeparaffinisationXylene, graded ethanol series to water (standard)
Antigen retrievalHeat retrieval: EDTA pH 8.0 (datasheet A03412-1); 20 min, 95–100 °C (standard)
Peroxidase block3% H2O2, 10 min, room temperature (standard)
Blocking10% goat serum (datasheet A03412-1)
Primary antibodyRabbit anti-CCAR2, 1-2 μg/ml (datasheet A03412-1)
Primary incubationOvernight at 4 °C (datasheet A03412-1)
DetectionStreptavidin-biotin complex (SABC), DAB chromogen (datasheet A03412-1)
CounterstainHematoxylin, blue, dehydrate and mount (standard)
Expected resultCCAR2-positive staining in respiratory epithelial cells of bronchus (HPA tissue IHC: High). HPA tissue profile: Ubiquitous nuclear expression. No signal in the no-primary control.
💡Decision noteStart with heat-mediated EDTA, pH 8.0, for the catalog antibody (datasheet A03412-1). The published protocols used different retrieval conditions (PMC13229996; PMC4335761; PMC5787426).
Section 2

What Is the Expected CCAR2 Staining Pattern?

CCAR2 should appear predominantly in nuclei across many cell types (HPA tissue IHC: ubiquitous nuclear expression; UniProt Q8N163: nucleus). Expect conspicuous staining in bronchial respiratory epithelium and cerebral cortical neurons (HPA tissue IHC: High). UniProt also records cytoplasmic and spindle localization in specific contexts (UniProt Q8N163: subcellular location). CCAR2 has no transmembrane segment, so a membrane outline is not its expected pattern (UniProt Q8N163: topology). HPA rates the tissue IHC profile Enhanced for agreement with RNA expression (HPA tissue IHC: reliability).

What am I looking at on my slide?
Distinct nuclear chromogen in bronchial respiratory epithelial cells, with nuclei identifiable by counterstain (HPA tissue IHC: High in bronchus).This fits the reported ubiquitous nuclear profile (HPA tissue IHC). Judge whether staining follows individual nuclei and the tissue architecture; HPA's High category describes the reported cell population, not a required chromogen darkness for every run (HPA tissue IHC; general IHC practice).
Predominantly membranous or uniformly cytoplasmic staining, with little nuclear signal.A membrane outline conflicts with CCAR2's lack of a transmembrane segment (UniProt Q8N163: topology). Cytoplasmic localization is reported with MCC or during UV-induced apoptosis, but those contexts cannot be inferred from appearance alone (UniProt Q8N163: subcellular location). Review controls before assigning this pattern to CCAR2 (general IHC practice).
Strong staining in lung alveolar cells while an expected positive cell population lacks nuclear signal.HPA reports CCAR2 as Not detected in alveolar cells, despite its broader ubiquitous nuclear profile (HPA tissue IHC: lung; profile). This mismatch raises possible cross-reactivity or endogenous detection activity; compare a known-positive section and detection controls before interpreting it as a biological exception (general IHC practice).
Diffuse chromogen covers nuclei, cytoplasm and surrounding tissue without clear cell boundaries.Diffuse background prevents a reliable nuclear call (general IHC practice; HPA tissue IHC: nuclear profile). Check the no-primary control and background in tissue compartments; excess detection reagent, incomplete blocking or insufficient washing are general possibilities, not documented CCAR2-specific effects (general IHC practice).
No nuclear signal in bronchial respiratory epithelium or another HPA High cell population.A blank known-positive population conflicts with the reported tissue pattern (HPA tissue IHC: bronchus, respiratory epithelial cells, High). First assess section integrity, positive-control performance and the staining run (general IHC practice). One negative section cannot establish that CCAR2 is absent from the sample.
💡Expected CCAR2 appearanceCall a convincing IHC positive when identifiable nuclei stain in an expected population, such as bronchial respiratory epithelial cells reported High (HPA tissue IHC); an isolated membrane rim or diffuse, cell-independent chromogen is a suspect positive (UniProt Q8N163: topology; general IHC practice).
How each factor affects the staining
Cell population and reference tissueHPA reports High staining in bronchial respiratory epithelium and cerebral cortical neurons, Low staining in pancreatic exocrine glandular cells, and Not detected in lung alveolar cells (HPA tissue IHC). Compare like cell populations; neighboring cells need not share an intensity category.
Antibody validationHPA lists HPA019907 and HPA019943 as IHC Enhanced, and CAB072827 as IHC Supported (HPA antibodies). These are validation summaries for those antibodies, not proof that every reagent or staining run will reproduce the tissue profile (HPA antibodies; general IHC practice).
Isoforms and protein modificationUniProt lists two CCAR2 isoforms and modified residues, including phosphorylation, acetylation and methylation (UniProt Q8N163). The payload gives no antibody epitope or IHC comparison across these forms, so their effect on staining cannot be predicted.
IF/ICC Q: Where should fluorescence appear?A: HPA reports nucleoplasm and nuclear bodies as enhanced locations in ICC-IF images (HPA subcellular ICC-IF). This supports a nuclear IF/ICC interpretation; it does not define an IHC antigen retrieval method, dilution or chromogenic intensity.
Why is my staining missing, weak or wrong?
SituationLikely causeNext action
Known-positive bronchial epithelium is blank.The result disagrees with HPA's High call for respiratory epithelial cells (HPA tissue IHC); a failed staining or detection step is possible (general IHC practice).Check that a same-run positive control stained, then review antibody application, detection reagents and counterstain. Optimize antigen retrieval against a positive control if needed; no CCAR2-specific retrieval condition or fixation sensitivity is supplied (general IHC practice).
Only lung alveolar cells stain strongly.HPA reports alveolar cells as Not detected (HPA tissue IHC: lung). Strong isolated staining may reflect cross-reactivity or endogenous detection activity (general IHC practice).Verify alveolar cell identity on the counterstained section; compare an expected positive population and a no-primary control before assigning the chromogen to CCAR2 (general IHC practice).
A crisp membrane rim dominates the slide.CCAR2 has no transmembrane segment, and HPA describes a ubiquitous nuclear IHC profile (UniProt Q8N163: topology; HPA tissue IHC).Inspect the no-primary control and repeat with an IHC-validated antibody if needed. Score nuclear signal separately from the membrane pattern (HPA antibodies: IHC validation; general IHC practice).
Cytoplasmic staining dominates while nuclei appear weak.UniProt reports cytoplasmic CCAR2 in specified contexts, including MCC presence and UV-induced apoptosis; the slide alone does not establish either context (UniProt Q8N163: subcellular location).Confirm nuclear staining in a same-run HPA High reference population, then evaluate background and antibody specificity before interpreting cytoplasmic signal (HPA tissue IHC; general IHC practice).
Chromogen is diffuse across the section.Background can obscure the nuclear profile reported by HPA (HPA tissue IHC; general IHC practice). Incomplete blocking or washing is a general workflow possibility (general IHC practice).Compare the no-primary control, check wash and blocking steps, and adjust antibody or detection conditions empirically with a positive reference section (general IHC practice).
A low-staining population is judged negative because it lacks strong chromogen.HPA distinguishes Low populations, including pancreatic exocrine glandular cells, from Not detected alveolar cells (HPA tissue IHC).Score the named cell population and its nuclear compartment against a same-run positive control; report weak or indeterminate staining separately from absent staining (HPA tissue IHC; general IHC practice).

Sample controls for CCAR2 IHC & IF

🧪Run bronchus first and assess respiratory epithelial cells for CCAR2 staining (HPA: High in respiratory epithelial cells). Use lung alveolar cells as the biological negative comparator (HPA: Not detected in alveolar cells); on the bronchus slide, cells without specific signal should show counterstained nuclei without distinct nuclear DAB staining (standard IHC practice).
Positive control tissue: Bronchus (Respiratory epithelial cells, HPA High)
Negative control tissue: Lung (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CCAR2 in A-431, U-251MG, U2OS, HeLa, MCF-7, U2OS, siRNA 1 (10x), U2OS, siRNA 2 (10x), U2OS, scrambled (10x), with annotated localisation: Nucleoplasm (enhanced), Nuclear bodies (enhanced) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a concentration-matched rabbit isotype control (caption: rabbit primary antibody; standard IHC practice); use CCAR2 knockout material processed alongside the test section as a target-specific negative control (standard IHC practice). Block endogenous peroxidase and assess endogenous biotin background because the caption uses biotin-based detection with DAB (caption: biotinylated secondary, SABC and DAB).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected-SKU tissue-IHC caption does not state its fixative (caption: fixative not stated). The reported paraffin-section procedure uses heat retrieval in EDTA at pH 8.0, but a requirement for that retrieval method across specimens is unreported (caption: EDTA retrieval, pH 8.0). The supplied evidence does not establish that frozen sections or IF are easier; for bronchus, check luminal mucus and epithelial edges against the negative controls for nonspecific DAB deposits (HPA: bronchus respiratory epithelial cells; standard IHC practice).

HPA tissue IHC evidence for CCAR2

Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — High 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

TissueCell typeLevelEvidenceSource
Bronchus Respiratory epithelial cells High Protein (IHC) HPA →
Cerebellum Cells in molecular layer High Protein (IHC) HPA →
Cerebral cortex Neuronal cells High Protein (IHC) HPA →
Epididymis Glandular cells High Protein (IHC) HPA →
Esophagus Squamous epithelial cells High Protein (IHC) HPA →

Undetected expression · recommended negative controls

TissueCell typeLevelEvidenceSource
Lung Alveolar cells Not detected Protein (IHC) HPA →
Section 3

Advanced CCAR2 IHC Tips

Troubleshoot CCAR2 staining in paraffin sections by checking retrieval, compartment, controls and scoring against the expected nuclear pattern (HPA: tissue IHC).

How should I adjust retrieval when CCAR2 nuclear staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin-section CCAR2 IHC (datasheet A03412-1). The selected tissue image used this retrieval before an overnight incubation with 2 μg/ml antibody at 4°C, so compare weak runs against those documented conditions (datasheet A03412-1). Check that sections remain attached and that heating and cooling are consistent across slides, because uneven retrieval can mimic patchy antigen expression (standard IHC practice). If staining remains weak, compare a small retrieval-time series while holding antibody concentration and detection constant (standard IHC practice). Judge improvement by clean nuclear staining in expected cells, rather than stronger diffuse color (HPA: ubiquitous nuclear expression; standard IHC practice).
Can fixation explain weak or variable CCAR2 staining?
The selected CCAR2 image describes a paraffin-embedded section but does not report its fixative, so target-specific fixation sensitivity is unknown (datasheet A03412-1). Record the actual fixative, fixation duration and processing history for each specimen before comparing staining between cases (standard IHC practice). Use sections processed together and hold EDTA retrieval at pH 8.0 constant while assessing whether weak nuclei track with a processing batch (datasheet A03412-1; standard IHC practice). Check morphology and an independent nuclear control stain to identify broadly compromised sections (standard IHC practice). A fixation effect requires a controlled comparison; neither CCAR2 tissue distribution nor its modifications establish one (HPA: tissue IHC; UniProt Q8N163: modified residues).
Should cytoplasmic CCAR2 staining count as a positive IHC result?
Prioritize nuclear staining when scoring routine paraffin sections, because tissue IHC reports ubiquitous nuclear expression and cell imaging places CCAR2 in nucleoplasm and nuclear bodies (HPA: tissue IHC and subcellular). CCAR2 can also localize to cytoplasm or spindle, with cytoplasmic sequestration reported in the presence of MCC and translocation during UV-induced apoptosis (UniProt Q8N163: subcellular location). Thus, a cytoplasmic pattern warrants review of cell morphology and biological context before inclusion in the primary nuclear score (UniProt Q8N163: subcellular location; standard IHC practice). Compare it with adjacent intact nuclei, background and a control section processed in the same run (standard IHC practice). Report nuclear and cytoplasmic observations separately (standard IHC practice).
Could isoforms or epitope masking explain discordant CCAR2 staining?
CCAR2 has 2 listed isoforms, but the supplied antibody record does not map this product’s epitope to either isoform (UniProt Q8N163: isoforms; datasheet A03412-1). Do not assign an isoform from chromogenic staining intensity alone (standard IHC practice). CCAR2 also has annotated phosphorylation, acetylation and methylation sites, yet no supplied evidence shows that these modifications change recognition by this antibody (UniProt Q8N163: modified residues; datasheet A03412-1). If staining disagrees with another assay, compare antibody immunogens or epitope maps when available and repeat the established EDTA pH 8.0 retrieval consistently (datasheet A03412-1; standard IHC practice). Treat a compartment shift separately from an apparent loss of signal (UniProt Q8N163: subcellular location; standard IHC practice).
How can IF help resolve ambiguous chromogenic CCAR2 localization?
Use IF as a separate localization check when chromogenic nuclear and cytoplasmic signals are difficult to distinguish (standard IF practice). Pair CCAR2 with a marker for the expected cell type in the specimen; gallbladder glandular cells are one documented high-staining population (HPA: gallbladder glandular cells, High; standard IF practice). Choose spectrally separated fluorophores and place the weaker signal in a channel with low tissue autofluorescence, confirming that choice with an unstained section (standard IF practice). Because CCAR2 has no transmembrane segment and is reported in nuclear and cytoplasmic compartments, use permeabilization suited to intracellular epitope access (UniProt Q8N163: topology and subcellular location; standard IF practice). Compare the IF pattern with the IHC nuclear score without assuming identical assay sensitivity (standard IF/IHC practice).
What should I check when CCAR2 DAB staining looks diffuse?
The selected chromogenic workflow uses a biotinylated secondary, a streptavidin-biotin complex and DAB, so inspect background at each detection stage (datasheet A03412-1). Include a no-primary control to reveal secondary or detection-system signal, and check endogenous peroxidase blocking before DAB development (standard IHC practice). If background persists, assess endogenous biotin with the relevant detection controls and review blocking and wash steps; the selected image used 10% goat serum (datasheet A03412-1; standard IHC practice). Avoid treating uniform cytoplasmic haze or staining over empty spaces as CCAR2 positivity when the expected tissue pattern is nuclear (HPA: ubiquitous nuclear expression; standard IHC practice). Compare controls and test sections using the same development time (standard IHC practice).
How should I score CCAR2 across heterogeneous tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, then record the percentage of positive nuclei and nuclear intensity in each region (HPA: ubiquitous nuclear expression; standard IHC practice). An H-score can combine intensity categories 0–3 with their percentages to give 0–300; report the scoring rule alongside results (standard IHC practice). Normalize positive counts to the number of evaluable cells in the chosen population, or report positive-cell density per mm² of evaluable tissue when area is the denominator (standard IHC practice). Exclude folds, necrosis and section edges by a stated rule applied to every case (standard IHC practice). Keep any cytoplasmic score separate because CCAR2 localization can change with context (UniProt Q8N163: subcellular location).
How do I distinguish genuine CCAR2 signal from artefact?
A credible routine positive shows staining in intact nuclei within the scored cell population, consistent with the reported ubiquitous nuclear tissue pattern (HPA: tissue IHC; standard IHC practice). Bronchial respiratory epithelial cells and gallbladder glandular cells are documented high-staining examples, whereas lung alveolar cells were not detected in the cited tissue profile (HPA: bronchus, High; gallbladder, High; lung alveolar cells, Not detected). Review staining confined to section edges, necrotic areas or the wrong cell population before calling it positive (standard IHC practice). Use a no-primary control and peroxidase-control checks to separate chromogen or endogenous enzyme signal from antibody-dependent staining (standard IHC practice). Interpret convincing cytoplasmic staining cautiously because CCAR2 can redistribute under specified conditions (UniProt Q8N163: subcellular location).
Boster reagents

Best CCAR2 / Cell cycle and apoptosis regulator protein 2 IHC Antibodies

The catalog antibodies cover paraffin-section IHC in human cancer tissue and mouse brain, plus IF/ICC in U20S cells (A03412-1 and A30523 image captions).

Real IHC data IHC analysis of DBC-1/CCAR2 using anti-DBC-1/CCAR2 antibody (A03412-1). DBC-1/CCAR2 was detected in a paraffin-embedded section of human gall bladder adenosquamous carcinoma tissue. Heat mediated antigen retrieval was performed in EDTA buffer (pH 8.0, epitope retrieval solution). The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 2 μg/ml rabbit anti-DBC-1/CCAR2 Antibody (A03412-1) 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.
Anti-DBC-1/CCAR2 Antibody ®
Cat # A03412-1
Real IHC data Immunohistochemical analysis of paraffin-embedded human liver cancer. 1, Antibody was diluted at 1:200(4° overnight). 2, Tris-EDTA,pH9.0 was used for antigen retrieval. 3,Secondary antibody was diluted at 1:200(room temperature, 45min).
Anti-KIAA1967 CCAR2 Antibody
Cat # A30523

A03412-1 has IHC images from human gall bladder adenosquamous carcinoma, liver cancer, lung cancer, and mouse brain, plus an IF/ICC image from U20S cells (A03412-1 image captions). A30523 has an IHC image from paraffin-embedded human liver cancer and lists IF/ICC as applications without an IF image (A30523 image caption; catalog applications).

Which to pick: For tissue IHC across the pictured samples, choose A03412-1; its IHC images document paraffin sections from human cancers and mouse brain (A03412-1 IHC image captions). For IF/ICC, choose A03412-1 when a pictured cell staining example matters; A30523 also lists IF/ICC and is described as polyclonal, but has no IF image in the payload (A03412-1 IF image caption; A30523 catalog applications and dilution record). For cross-species planning, A03412-1 lists human, mouse, rat, and monkey reactivity, while A30523 lists human, mouse, and rat; the IHC captions report paraffin sections but do not report the fixative (catalog reactivity; A03412-1 and A30523 IHC image captions).

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

References

  1. UniProt Consortium. UniProt entry Q8N163 (CCAR2_HUMAN, Cell cycle and apoptosis regulator protein 2).
  2. Human Protein Atlas. CCAR2 tissue IHC expression (reliability: Enhanced).
  3. Human Protein Atlas. CCAR2 subcellular location (ICC-IF): Localized to the nucleoplasm and nuclear bodies..
  4. Human Protein Atlas. CCAR2 antibody validation summary (4 antibodies).
  5. Sirtuin 1 stimulates the proliferation and the expression of glycolysis genes in pancreatic neoplastic lesions. Oncotarget 2016 — PMC5342700.
  6. An anoikis-related gene signature predicts prognosis and immunotherapy response, and identifies CCAR2 as a therapeutic target in triple-negative breast cancer. Frontiers in immunology 2026 — PMC13229996.
  7. The expression of DBC1/CCAR2 is associated with poor prognosis of ovarian carcinoma. Journal of ovarian research 2015 — PMC4335761.
  8. CCAR2 negatively regulates IL-8 production in cervical cancer cells. Oncotarget 2018 — PMC5787426.
  9. PubMed PMID:14702039 — UniProt-cited evidence.
  10. PubMed PMID:17974005 — UniProt-cited evidence.
  11. PubMed PMID:16421571 — UniProt-cited evidence.