CYP2E1 / Cytochrome P450 2E1 · IHC design guide

Design Immunohistochemistry for CYP2E1

Plan chromogenic CYP2E1 IHC in paraffin sections using hepatocyte cytoplasmic staining as the expected pattern (HPA tissue IHC). The catalog antibody has an IHC dilution of 0.5–1 µg/mL (datasheet A00672).

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

Immunohistochemistry protocol sheet for CYP2E1 (IHC for CYP2E1): expected localisation Hepatocyte cytoplasm (HPA tissue IHC); ER and mitochondrial inner membrane (UniProt), antibody A00672, validated IHC image, and IHC protocol steps — Printable **CYP2E1** IHC protocol sheet — expected localisation Hepatocyte cytoplasm (HPA tissue IHC); ER and mitochondrial inner membrane (UniProt), antibody A00672, controls and protocol steps. Open the full CYP2E1 IHC guide →

Navigate to: Protocols Staining pattern Controls Antibodies

CYP2E1 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	Hepatocyte cytoplasm (HPA tissue IHC); ER and mitochondrial inner membrane (UniProt)
	Staining pattern	Selective cytoplasmic staining in hepatocytes (HPA tissue IHC)
	Antigen retrieval	Citrate pH 6 HIER, heat-mediated (datasheet A00672)
	Positive control ⓘ	Liver
	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	Endogenous liver peroxidase can add DAB background (standard IHC practice)
	Regulation	Expression regulation not annotated (UniProt)
	Isoform / epitope	No annotated isoforms; one 1–493 chain (UniProt)

Section 1

Recommended CYP2E1 IHC & IF Protocols

Compare the catalog antibody’s IHC-P protocol (datasheet A00672) with published CYP2E1 protocols for bone marrow (PMC3447587) and liver (PMC6682552; PMC5177661; PMC4660393).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	Paraffin-embedded human liver cancer tissues; fixative not specified (datasheet A00672)
Fixation	Image fixative and duration unreported (datasheet A00672); verify before use.
Sectioning	4–5 µm sections on charged slides (standard)
Deparaffinisation	Xylene, graded ethanol series to water (standard)
Antigen retrieval	Heat retrieval: Citrate pH 6, 20 min (datasheet A00672)
Peroxidase block	3% H2O2, 10 min, room temperature (standard)
Blocking	10% goat serum (datasheet A00672)
Primary antibody	Rabbit anti-CYP2E1, 0.5-1μg/ml (datasheet A00672)
Primary incubation	Overnight at 4 °C (datasheet A00672)
Detection	Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A00672)
Counterstain	Hematoxylin, blue, dehydrate and mount (standard)
Expected result	CYP2E1-positive staining in hepatocytes of liver (HPA tissue IHC: High). HPA tissue profile: Selective cytoplasmic expression in hepatocytes. No signal in the no-primary control.

💡Decision noteStart with heat-mediated citrate retrieval at pH 6 (datasheet A00672); published protocols use citrate at pH 6.1 and pH 6.0 (PMC3447587; PMC6682552).

Section 2

What Is the Expected CYP2E1 Staining Pattern?

In paraffin-section IHC, CYP2E1 should stain hepatocyte cytoplasm strongly; the HPA tissue profile is Enhanced and reports selective, High hepatocyte staining in liver (HPA: tissue IHC). Its ER and microsomal membrane association, with some protein at the mitochondrial inner membrane, supports an intracellular pattern (UniProt P05181: localization). UniProt annotates no transmembrane segment (UniProt P05181: topology).

What am I looking at on my slide?
Strong cytoplasmic staining in liver hepatocytes, with the signal contained within those cells (HPA: High in hepatocytes).	This matches the reported selective hepatocyte pattern (HPA: tissue IHC). Interpret the chromogenic signal at the cell level: routine IHC may not resolve ER from mitochondria even though both are reported CYP2E1 locations (UniProt P05181: localization; standard IHC practice).
Predominantly nuclear staining, with little hepatocyte cytoplasmic signal (HPA: expected hepatocyte pattern).	That distribution conflicts with HPA cytoplasmic staining and the UniProt ER, microsomal, and mitochondrial locations (HPA: tissue IHC; UniProt P05181: localization). Treat it as a suspected staining artefact; check controls and repeat before assigning nuclear CYP2E1 (standard IHC practice).
Strong staining in non-hepatocytes, or in a cell population HPA reports as Not detected (HPA: tissue IHC).	The result falls outside the supplied reference pattern. For example, HPA reports no detection in adipocytes from adipose tissue or glandular cells from adrenal gland (HPA: tissue IHC). Investigate antibody cross-reactivity and detection background; an HPA negative result is not proof that every specimen must be negative (standard IHC interpretation).
Diffuse chromogen covers tissue and background, obscuring cell boundaries (standard IHC practice).	The slide cannot establish selective hepatocyte staining under these conditions. Check the no-primary control, wash and blocking steps, and chromogen development; tissue-associated endogenous detection activity can also contribute to background (standard chromogenic IHC practice).
No hepatocyte signal in a well-preserved liver section expected to be positive (HPA: High in hepatocytes).	A blank slide does not by itself establish biological absence. First verify the detection controls, antibody conditions, retrieval procedure, and section quality (standard IHC practice). The supplied sources do not report a CYP2E1-specific fixation sensitivity, so do not attribute the loss to fixation without further evidence.

💡Expected CYP2E1 appearanceCall a result positive when hepatocytes show High, selective cytoplasmic staining (HPA: tissue IHC); predominantly nuclear signal or equally strong diffuse staining outside hepatocytes is discordant and warrants control checks (HPA: tissue IHC; standard IHC practice).

How each factor affects the staining
Reference tissue and cell type	Liver hepatocytes are the supplied positive reference: HPA reports High staining and liver-enriched RNA (HPA: tissue IHC). The listed negative cell populations are comparators, subject to specimen and assay context (HPA: tissue IHC; standard IHC interpretation).
Subcellular distribution	UniProt places CYP2E1 at ER and microsomal membranes and reports post-translational mitochondrial targeting to the inner membrane (UniProt P05181: localization). These locations support cytoplasmic staining; chromogenic IHC alone may not distinguish the organelles (standard IHC practice).
IHC antibody evidence	HPA marks IHC staining with HPA009128 and HPA029564 as Enhanced (HPA: antibodies). The tissue profile reports high consistency between staining and RNA expression (HPA: reliability); those summaries support the reference pattern, not every individual staining run.
IF/ICC question: what pattern is expected?	HPA approves ER and mitochondrial localization in ICC-IF and lists HEK293, HaCaT, and serum-starved hTERT-RPE1 image sets (HPA: subcellular). This organelle evidence can guide interpretation, but IF/ICC assay conditions belong to its separate guide.
Chromogenic detection background	Endogenous enzyme activity can create chromogen signal in tissue; a no-primary control helps distinguish detection background from antibody-dependent staining (standard chromogenic IHC practice). This is a general assay consideration, not a CYP2E1-specific finding.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Liver hepatocytes are blank despite an expected High signal (HPA: tissue IHC).	Possible assay failure or unsuitable antibody, retrieval, or detection conditions (standard IHC practice).	Review the IHC-validated antibody's instructions, confirm reagent and detection controls, and assess section quality. Record any retrieval changes as assay optimization; the supplied sources give no CYP2E1-specific fixation effect (standard IHC practice).
Nuclei stain more strongly than hepatocyte cytoplasm (HPA: expected cytoplasmic pattern).	The compartment conflicts with HPA tissue IHC and UniProt localization; nonspecific staining is possible (HPA: tissue IHC; UniProt P05181: localization; standard IHC practice).	Check the no-primary control and counterstain, then reassess antibody concentration and detection conditions before interpreting a nuclear signal (standard IHC practice).
Most cell types stain at similar intensity, obscuring selectivity (HPA: selective hepatocyte pattern).	Excess antibody signal or background can erase the expected contrast (standard IHC practice).	Compare hepatocytes with adjacent cells, inspect the no-primary control, and optimize antibody dilution and washing against the catalog antibody's IHC instructions (standard IHC practice).
Chromogen appears where the primary antibody was omitted (standard IHC control).	The signal arises from detection chemistry or endogenous tissue activity rather than primary-antibody binding (standard chromogenic IHC practice).	Check detection reagents, blocking, washing, and chromogen development; repeat the no-primary control alongside the stained section (standard chromogenic IHC practice).
Adipocytes from adipose tissue or adrenal glandular cells stain strongly (HPA: Not detected in these populations).	The result differs from the HPA reference and may reflect cross-reactivity or assay background; specimen variation remains possible (HPA: tissue IHC; standard IHC interpretation).	Verify cell identity and compare no-primary controls, then evaluate staining with an independently validated antibody if available (standard IHC practice). Do not call the signal CYP2E1 solely from its color.
A granular cytoplasmic pattern is difficult to assign to one organelle (UniProt P05181: localization).	ER and mitochondrial CYP2E1 locations overlap at the level of a chromogenic tissue section (UniProt P05181: localization; standard IHC practice).	Score the supported hepatocyte cytoplasmic result in IHC; use the separate IF/ICC guide for organelle-level assessment, informed by HPA-approved ER and mitochondrial localization (HPA: subcellular; standard IHC practice).

Source: UniProt P05181 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing CYP2E1 staining

IHC analysis of CYP2E1 using anti-CYP2E1 antibody (A00672). CYP2E1 was detected in paraffin-embedded section of human liver cancer tissues. Heat mediated antigen retrieval was performed in citrate buffer (pH6, epitope retrieval solution) for 20 mins. The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml rabbit anti-CYP2E1 Antibody (A00672) 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.

A00672 · IHCIHC analysis of CYP2E1 using anti-CYP2E1 antibody (A00672). CYP2E1 was detected in paraffin-embedded section of human liver cancer tissues.

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000130649-CYP2E1/tissue/cerebral+cortex#imid_7247496

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000130649-CYP2E1/tissue/colon#imid_7255566

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000130649-CYP2E1/tissue/liver#imid_2672463

HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000130649-CYP2E1/tissue/kidney#imid_7255576

HPA · ICC-IF HEK293Human Protein Atlas immunofluorescence, HEK293, antibody HPA029564; green = CYP2E1, blue = nucleus, red = microtubules.

← swipe / scroll for more images →

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

Sample controls for CYP2E1 IHC & IF

🧪Run liver first and expect staining in hepatocytes (HPA: High in hepatocytes); use adipose tissue as the negative comparator (HPA: Not detected in adipocytes). On the liver slide, adjacent non-hepatocyte cells should provide a low-background reference, but their CYP2E1-negative status is unverified (HPA: High in hepatocytes).

Positive control tissue: Liver (Hepatocytes, HPA High)

Negative control tissue: Adipose tissue (HPA Not detected)

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CYP2E1 in HEK293, HaCaT, hTERT-RPE1 (serum starved), with annotated localisation: Endoplasmic reticulum (approved), Mitochondria (approved) (HPA subcellular).

Technical controls: Include a no-primary, secondary-only control and a concentration-matched rabbit IgG isotype control (caption: rabbit primary antibody); use CYP2E1 knockout tissue, if available, as a biological specificity control. Block endogenous peroxidase and check for endogenous biotin background in liver when using the caption’s biotin-based DAB detection (caption: biotinylated secondary, SABC and DAB).

⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A00672 paraffin-section caption does not state the fixative (caption: fixative unreported). The caption uses heat retrieval in citrate buffer at pH 6 for 20 minutes, so verify retrieval under local conditions (caption: citrate retrieval); the supplied evidence does not establish that frozen sections or IF are easier. Check liver background carefully with the stated biotin-based DAB method (caption: SABC and DAB).

HPA tissue IHC evidence for CYP2E1

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

Tissue	Cell type	Level	Evidence	Source
Liver	Hepatocytes	High	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 →
Appendix	Glandular cells	Not detected	Protein (IHC)	HPA →
Bone marrow	Hematopoietic cells	Not detected	Protein (IHC)	HPA →
Breast	Adipocytes	Not detected	Protein (IHC)	HPA →

Section 3

Advanced CYP2E1 IHC Tips

Troubleshoot CYP2E1 staining against the catalog antibody’s paraffin-section conditions, hepatocyte expression, and expected intracellular localisation.

How should I adjust retrieval when CYP2E1 staining is weak?

Start with heat-mediated citrate retrieval at pH 6 for 20 minutes (datasheet A00672). The selected paraffin-section image used this condition with 1 μg/mL catalog antibody overnight at 4°C; keep those incubation settings consistent while assessing retrieval (caption A00672). Compare adjacent sections with modest changes around 20 minutes, recording both cytoplasmic signal and tissue damage (standard IHC practice; HPA: selective cytoplasmic expression in hepatocytes). If staining remains weak, test another validated buffer as a fallback and retain it only if signal improves without added background (standard IHC practice). Include a no-primary control to identify detection-related staining (standard IHC practice).

Could fixation explain weak or uneven CYP2E1 IHC staining?

Target-specific fixation sensitivity is unknown from the supplied evidence; the selected image identifies paraffin sections but does not state a fixative (caption A00672). Record the fixative and fixation duration for each specimen, and compare sections processed under matched conditions before attributing differences to CYP2E1 abundance (standard IHC practice). If fixation varies, assess a positive control alongside each batch using the same pH 6 citrate retrieval and 20-minute heating step (datasheet A00672; standard IHC practice). Check morphology and no-primary controls before increasing antibody concentration, since weak staining or haze alone does not establish a fixation effect (standard IHC practice).

What CYP2E1 staining pattern should I expect in paraffin sections?

Expect predominantly cytoplasmic hepatocyte staining when evaluating liver sections (HPA: selective cytoplasmic expression in hepatocytes; HPA: high in hepatocytes). CYP2E1 is associated with the endoplasmic reticulum and microsomes and can also reach the mitochondrial inner membrane (UniProt P05181: subcellular location). Its mitochondrial pool is targeted after translation and associates with that membrane as a membrane-extrinsic protein; the record annotates no transmembrane segment (UniProt P05181: targeting and topology). Judge the chromogenic pattern against cell morphology rather than trying to distinguish these organelles from DAB alone (standard IHC practice). Predominantly nuclear or extracellular staining warrants review of background and detection controls (UniProt P05181: subcellular location; standard IHC practice).

How can I assess whether the antibody epitope remains accessible?

The supplied record describes one 493-amino-acid chain and annotates 0 isoforms, without defining this antibody’s epitope (UniProt P05181: processing and isoforms; caption A00672). Do not assign weak staining to an isoform or a specific masked residue without independent epitope information (standard IHC practice). The record annotates 0 glycosylation sites and 0 modified residues, but those annotations cannot establish epitope accessibility after section processing (UniProt P05181: glycosylation and modified residues; standard IHC practice). Compare retrieval conditions on adjacent sections while holding antibody concentration and detection constant, then check whether improved staining preserves the expected hepatocyte cytoplasmic pattern (datasheet A00672; HPA: tissue IHC profile; standard IHC practice).

How should I use IF to investigate an ambiguous IHC pattern?

On the separate IF/ICC workflow, multiplex CYP2E1 with a validated hepatocyte marker when comparing the expected cell population in liver tissue (HPA: high hepatocyte expression; standard IF practice). Choose spectrally separated fluorophores and measure unstained tissue autofluorescence before assigning a weak CYP2E1 channel, especially when interpreting diffuse signal (standard IF practice). Optimise permeabilisation according to the antibody epitope’s accessible side of the relevant membrane; that side is not specified here, although CYP2E1 occupies ER-associated and mitochondrial locations (UniProt P05181: subcellular location; standard IF practice). Include single-channel and no-primary controls to distinguish overlap from bleed-through or background, and avoid inferring IF performance from the paraffin-section IHC caption (caption A00672; standard IF practice).

How can I reduce diffuse or granular DAB background?

Use a no-primary section to check detection-system background before changing the catalog antibody concentration (standard IHC practice). In the selected image, sections received 10% goat serum blocking, 1 μg/mL primary antibody overnight at 4°C, and biotin-based DAB detection (caption A00672). For a peroxidase-based workflow, check the peroxidase block and control DAB development time; these are general IHC safeguards, not CYP2E1-specific findings (standard IHC practice). If background persists, assess blocking, secondary-reagent controls, washing and endogenous biotin where relevant to that detection system (standard IHC practice). Preserve the expected hepatocyte cytoplasmic signal when adjusting these steps (HPA: tissue IHC profile; standard IHC practice).

How should I quantify CYP2E1 staining across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION

Define the scored cell population and tissue region before measuring stain, and exclude folds, edges and necrotic areas by a consistent rule (standard IHC practice). For hepatocytes, report both the percentage positive and an intensity-weighted H-score, using the same thresholds across sections (HPA: high hepatocyte expression; standard IHC practice). If counting positive cells, express density per mm² of evaluable tissue and identify the cell population counted (standard IHC practice). Normalise to evaluable hepatocyte area or hepatocyte count, and compare batches against a common control processed with the same retrieval and DAB settings (datasheet A00672; standard IHC practice). Record exposure-independent image settings and blinded scoring rules where applicable (standard IHC practice).

How do I distinguish true CYP2E1 staining from artefact?

A credible positive pattern is cytoplasmic staining in hepatocytes, consistent with the enhanced tissue IHC profile and liver-enriched RNA evidence (HPA: tissue IHC and RNA specificity). ER and mitochondrial association supports an intracellular pattern, but DAB localisation alone cannot assign an individual organelle (UniProt P05181: subcellular location; standard IHC practice). Treat predominant nuclear, extracellular, edge-only or necrotic staining as suspicious until morphology and controls are reviewed (UniProt P05181: subcellular location; standard IHC practice). Compare a known positive section with a no-primary control and assess endogenous peroxidase or biotin contributions when using the selected biotin-based DAB workflow (caption A00672; standard IHC practice). Interpret unexpected cells cautiously because the supplied evidence establishes a hepatocyte pattern, not universal absence elsewhere (HPA: tissue IHC profile).

Boster reagents

Best CYP2E1 / Cytochrome P450 2E1 IHC Antibodies

The catalog lists anti-CYP2E1 antibodies for IHC in human, mouse and rat (catalog applications/reactivity). Real paraffin-section IHC images show human liver cancer and mouse liver with A00672 (A00672 image captions).

Real IHC data

Anti-Cytochrome P450 2E1/CYP2E1 Antibody ®

Cat # A00672

View product →

A00672 lists IHC for human, mouse and rat (A00672 catalog applications/reactivity), with paraffin-section images from human liver cancer and mouse liver (A00672 image captions). M00672 lists IHC and human, mouse and rat reactivity (M00672 catalog applications/reactivity), but has no supplied IHC image (M00672 image alts).

Which to pick: Choose A00672 for paraffin-section tissue IHC because its own captions document staining in human liver cancer and mouse liver after citrate retrieval (A00672 image captions); M00672 is a rabbit monoclonal option, clone AADC-3, listed for IHC without a supplied IHC figure (M00672 catalog/image alts). Neither SKU lists IF/ICC validation or supplies an IF figure (catalog applications/IF image alts). For cross-species IHC, both list human, mouse and rat reactivity (catalog reactivity), while the pictured evidence covers human and mouse with A00672 (A00672 image captions); the fixative is unreported (A00672 image captions).

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

References

UniProt Consortium. UniProt entry P05181 (CP2E1_HUMAN, Cytochrome P450 2E1).
Human Protein Atlas. CYP2E1 tissue IHC expression (reliability: Enhanced).
Human Protein Atlas. CYP2E1 subcellular location (ICC-IF): Localized to the endoplasmic reticulum and mitochondria..
Human Protein Atlas. CYP2E1 antibody validation summary (2 antibodies).
Over-expression of CYP2E1 mRNA and protein: implications of xenobiotic induced damage in patients with de novo acute myeloid leukemia with inv(16)(p13.1q22); CBFβ-MYH11. International journal of environmental research and public health 2012 — PMC3447587.
A chronic toxicity study of diphenylarsinic acid in the drinking water of C57BL/6J mice for 52 weeks. Journal of toxicologic pathology 2019 — PMC6682552.
Development of an IgY Antibody-Based Immunoassay for the Screening of the CYP2E1 Inhibitor/Enhancer from Herbal Medicines. Frontiers in pharmacology 2016 — PMC5177661.
Adaptation to acetaminophen exposure elicits major changes in expression and distribution of the hepatic proteome. Scientific reports 2015 — PMC4660393.
PubMed PMID:3782137 — UniProt-cited evidence.
PubMed PMID:3233219 — UniProt-cited evidence.
PubMed PMID:15164054 — UniProt-cited evidence.