CYP2E1 / Cytochrome P450 2E1 · IHC design guide

Design Immunohistochemistry for CYP2E1

Use liver hepatocytes as the positive reference for selective cytoplasmic CYP2E1 staining (HPA tissue IHC). This paraffin-section IHC guide covers fixation, the IHC-validated antibody at 0.5–1 μg/mL (datasheet: A00672), chromogenic detection, and endogenous peroxidase blocking (standard IHC practice).

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 →

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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 paraffin-section fixation consistent (standard IHC practice; not target-specific); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A00672)
	Caveat	Endogenous peroxidase can confound liver DAB staining (standard IHC practice)
	Regulation	Expression regulation is not annotated (UniProt)
	Isoform / epitope	No annotated isoforms; one 1–493 chain (UniProt)

Section 1

Recommended CYP2E1 IHC & IF Protocols

The catalog antibody’s IHC-P protocol (datasheet: A00672) is followed by 4 published CYP2E1 IHC protocols (PMC3447587; 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); two published protocols also use citrate near pH 6 (PMC3447587; PMC6682552).

Section 2

What Is the Expected CYP2E1 Staining Pattern?

CYP2E1 should show selective cytoplasmic staining in hepatocytes, with high signal in liver (HPA tissue IHC: Enhanced; HPA: High in hepatocytes). Its reported locations are the endoplasmic reticulum and mitochondria (UniProt P05181; HPA subcellular: approved). UniProt lists no transmembrane segment despite its membrane association (UniProt P05181 topology).

What am I looking at on my slide?
Strong cytoplasmic chromogen in hepatocytes, with surrounding structures readily distinguishable.	This matches the selective, High hepatocyte pattern reported for liver (HPA tissue IHC: Enhanced). Score the stained cells and their compartment together; intensity alone cannot establish specificity (general IHC practice).
Predominantly nuclear staining, or a sharp cell-surface outline without convincing hepatocyte cytoplasm.	That compartment conflicts with the reported cytoplasmic tissue pattern and ER/mitochondrial locations (HPA tissue IHC; HPA subcellular). Treat it as suspect and check the detection controls before assigning CYP2E1 positivity (general IHC practice).
Strong signal in cells other than hepatocytes, including a listed HPA-negative cell type.	HPA describes selective hepatocyte expression and reports several specified cell types as Not detected (HPA tissue IHC). Cross-reactivity or endogenous detection activity is possible; a negative result in one listed cell type does not establish that every other cell type must be negative (general IHC practice).
A uniform haze covers tissue, blank regions, or many cell types without a recognizable cytoplasmic pattern.	This is difficult to reconcile with selective hepatocyte staining (HPA tissue IHC). Background from detection or incomplete blocking is plausible; compare a no-primary control and assess whether signal follows tissue structures (general IHC practice).
No hepatocyte signal in an otherwise intact liver section.	Liver is the supplied positive reference, with High hepatocyte staining (HPA tissue IHC). First verify that hepatocytes and the detection system are evaluable; absence of signal alone cannot distinguish a technical failure from a specimen-specific result (general IHC practice).

💡Expected CYP2E1 appearanceCall positive when liver hepatocytes show High, selective cytoplasmic staining (HPA tissue IHC); nuclear-only, cell-surface-only, or uniform background signal is suspect against the reported ER/mitochondrial localization (HPA subcellular; UniProt P05181).

How each factor affects the staining
Tissue reference	Liver hepatocytes provide the strongest supplied positive reference (HPA tissue IHC: High; Enhanced). The listed Not detected observations apply to the named cells in those tissues, not to every cell in each organ (HPA tissue IHC).
Subcellular interpretation	ER and mitochondrial localization supports a cytoplasmic readout; UniProt also describes post-translational mitochondrial targeting and inner-membrane association (HPA subcellular: approved; UniProt P05181). Routine chromogenic IHC cannot reliably resolve those organelles individually (general IHC practice).
Antibody evidence	Both listed antibodies have Enhanced IHC validation; only HPA029564 also has Approved ICC status (HPA antibodies). These ratings support their reported applications, but do not supply a dilution, retrieval condition, or proof that every observed signal is specific.
IF/ICC: where should signal appear?	Expect ER- and mitochondria-associated signal (HPA subcellular: approved). HPA lists ICC-IF images from HEK293, HaCaT, and serum-starved hTERT-RPE1 cells; the supplied record gives no cell-specific intensity comparison or IF protocol (HPA subcellular).
Retrieval and fixation	The supplied HPA and UniProt records give no CYP2E1-specific retrieval condition or fixation-sensitivity result. If optimization is needed, evaluate retrieval against liver-positive and no-primary controls as general IHC practice; do not infer a target-specific fixation effect.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Liver hepatocytes are blank.	The expected positive reference is missing (HPA tissue IHC: High in hepatocytes); the cause cannot be identified from staining absence alone.	Check section integrity, antibody application, retrieval, and chromogenic detection with appropriate controls (general IHC practice). Reassess a liver reference before calling the specimen negative.
Nuclei dominate the signal.	A nuclear pattern conflicts with HPA's cytoplasmic liver staining and approved ER/mitochondrial locations (HPA tissue IHC; HPA subcellular).	Compare a no-primary control and inspect the counterstain and chromogen separately; repeat with an IHC-validated antibody if the pattern persists (general IHC practice; HPA antibodies: Enhanced IHC).
Non-hepatocyte cells stain as strongly as hepatocytes.	The pattern departs from selective hepatocyte expression (HPA tissue IHC); cross-reactivity or endogenous chromogenic activity may contribute (general IHC practice).	Identify the stained cell type, compare it with HPA's named cell-level observations, and run a no-primary control. If using peroxidase detection, check endogenous peroxidase blocking (general IHC practice).
Brown haze obscures cell boundaries.	Diffuse background prevents assessment of the selective cytoplasmic pattern (HPA tissue IHC); detection background is one possible cause (general IHC practice).	Compare tissue with a no-primary control, then review blocking, wash steps, and detection exposure one variable at a time (general IHC practice). Preserve a clear hepatocyte reference while adjusting conditions.
A proposed negative control shows staining.	HPA's Not detected calls concern specific tissue–cell pairs; an unmatched cell population may still be interpretable differently (HPA tissue IHC).	Confirm that the observed cells match a supplied Not detected pair. Then compare no-primary staining and hepatocyte positivity before attributing the signal to CYP2E1 (HPA tissue IHC; general IHC practice).
IF/ICC shows only diffuse fluorescence.	That appearance does not establish the ER and mitochondrial locations approved by HPA (HPA subcellular); background or limited spatial resolution may contribute (general IF practice).	Check the no-primary image and image acquisition settings, then assess whether signal follows ER and mitochondrial reference markers (general IF practice; HPA subcellular: approved).

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: hepatocytes should stain (HPA: High in hepatocytes). Run adipose tissue as the negative tissue, where adipocytes are not detected (HPA: Not detected in adipocytes); on the liver slide, use any unstained non-hepatocyte cells as an internal background reference, without assuming a particular cell type is negative.

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 host- and isotype-matched rabbit IgG control (A00672 caption: rabbit primary antibody), plus CYP2E1 knockout tissue as a biological specificity control. Block endogenous peroxidase and check endogenous biotin background when using the reported streptavidin–biotin/DAB detection method (A00672 caption: SABC with DAB).

⚠️Feasibility: The selected tissue-IHC caption does not state a fixative, and no target-specific fixation window or fixation effect is reported (A00672 caption: fixative not stated). Paraffin-section staining was shown after citrate retrieval at pH 6 for 20 minutes (A00672 caption); the supplied evidence does not establish whether frozen sections or IF are easier. In liver, assess endogenous peroxidase and biotin background with the reported SABC/DAB method (A00672 caption: SABC with 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

Use hepatocyte cytoplasmic staining as the reference pattern when troubleshooting CYP2E1 in paraffin sections (HPA tissue IHC).

What retrieval should I try first if CYP2E1 staining is weak?

Start with heat-mediated citrate retrieval at pH 6 for 20 minutes (datasheet A00672). The catalog antibody stained a paraffin-embedded human liver cancer section after that retrieval, followed by 1 μg/mL primary antibody overnight at 4°C (datasheet A00672). Compare retrieved and unretrieved sections from the same block while keeping detection and imaging conditions constant (standard IHC practice). If staining remains weak, adjust heating time on matched sections before considering another retrieval buffer as a fallback (standard IHC practice). Judge the result by selective hepatocyte cytoplasmic staining, alongside a no-primary control (HPA tissue IHC; standard IHC practice).

Could fixation explain weak or uneven CYP2E1 staining?

CYP2E1-specific sensitivity to fixation is unknown from the supplied evidence; the selected image identifies a paraffin-embedded section but does not report its fixative (datasheet A00672). Record the fixative, fixation duration, processing history and section age for each specimen before comparing staining intensity (standard IHC practice). Keep retrieval at citrate pH 6 for 20 minutes while assessing sections with different processing histories (datasheet A00672; standard IHC practice). Examine tissue preservation and staining uniformity with a counterstain, and include a consistently processed reference section in each run (standard IHC practice). Do not assign a CYP2E1-specific fixation effect without a direct comparison under otherwise matched conditions (standard IHC practice).

Which staining compartment supports a credible CYP2E1 result?

Look for cytoplasmic staining in hepatocytes, the selective tissue pattern reported for CYP2E1 (HPA tissue IHC). At finer resolution, CYP2E1 associates with the endoplasmic reticulum and mitochondria, so a purely nuclear pattern requires investigation (HPA subcellular; UniProt P05181; standard IHC practice). Its mitochondrial targeting occurs after translation, and the protein can associate with the inner mitochondrial membrane without an annotated transmembrane segment (UniProt P05181). Compare hepatocyte staining with adjacent tissue structures on the counterstained section rather than calling every brown deposit intracellular signal (HPA tissue IHC; standard IHC practice). Check suspected mislocalisation against a no-primary control and a well-preserved reference section processed in the same run (standard IHC practice).

Could epitope accessibility or an isoform explain discordant sections?

The supplied record lists one 1–493 chain and no annotated isoforms for CYP2E1, so isoform switching lacks support here (UniProt P05181). It also lists no annotated glycosylation sites or modified residues; those annotations do not establish how fixation affects this antibody’s epitope (UniProt P05181; standard IHC practice). The antibody’s epitope is not specified in the supplied caption, so its accessibility must be assessed empirically in paraffin sections (datasheet A00672; standard IHC practice). Begin with citrate pH 6 retrieval and matched control sections, then vary retrieval conditions one factor at a time if staining differs (datasheet A00672; standard IHC practice). Compare cellular distribution as well as intensity when judging whether a change improves specificity (HPA tissue IHC; standard IHC practice).

How can IF help assess an ambiguous chromogenic CYP2E1 pattern?

Use IF as a complementary localisation check when chromogenic IHC leaves the cellular source of CYP2E1 staining uncertain (standard IHC/IF practice). Multiplex CYP2E1 with a hepatocyte identity marker, since selective cytoplasmic hepatocyte expression is the expected tissue pattern (HPA tissue IHC; standard IF practice). Choose a fluorophore channel after checking unstained tissue for autofluorescence, and include single-label controls to assess channel bleed-through (standard IF practice). Optimise permeabilisation for the antibody epitope’s accessible side of the relevant membrane; that side is not specified by the supplied antibody caption (datasheet A00672; standard IF practice). Interpret overlap cautiously because CYP2E1 is reported at both endoplasmic reticulum and mitochondrial locations (HPA subcellular; UniProt P05181).

How do I reduce diffuse brown background without losing hepatocyte signal?

First compare the stained section with a no-primary control to distinguish detection background from antibody-dependent staining (standard IHC practice). The selected IHC example used 10% goat serum blocking, 1 μg/mL primary antibody overnight at 4°C, biotinylated secondary detection and DAB (datasheet A00672). If background is widespread, check blocking, washes, primary concentration and secondary detection on matched sections, changing one condition at a time (standard IHC practice). Include a peroxidase block for chromogenic detection and assess endogenous biotin when using a biotin-based system (standard IHC practice; datasheet A00672). Preserve a reference section to confirm that adjustments retain the expected hepatocyte cytoplasmic pattern (HPA tissue IHC; standard IHC practice).

How should CYP2E1 IHC be scored across heterogeneous sections? ⚠ ANSWER MARKED FOR VERIFICATION

Define the analysis region before scoring and identify hepatocytes by tissue morphology and counterstain (standard IHC practice; HPA tissue IHC). Record the percentage of positive hepatocytes and an intensity-based H-score, or measure positive staining area per mm² within the same defined compartment (standard IHC practice). Normalise area-based measurements to viable hepatocyte area or hepatocyte count, and apply identical thresholds, retrieval and DAB development across compared sections (standard IHC practice). Exclude necrotic, folded and detached regions using prespecified criteria, then report how much tissue was evaluable (standard IHC practice). Treat comparisons involving liver cancer tissue cautiously because the selected image demonstrates staining but supplies no matched quantitative baseline (datasheet A00672).

What separates true CYP2E1 staining from artefact in liver sections?

A credible result shows cytoplasmic hepatocyte staining, consistent with the reported selective tissue pattern and endoplasmic reticulum or mitochondrial localisation (HPA tissue IHC; HPA subcellular). Reassess predominantly nuclear staining, staining confined to unrelated cells, or signal concentrated at section edges or necrotic areas (HPA tissue IHC; standard IHC practice). Check a no-primary control for nonspecific detection and a peroxidase-blocked control when endogenous enzyme activity could produce DAB signal (standard IHC practice). Compare intact regions with similarly processed reference sections before attributing intensity differences to biological expression (standard IHC practice). The selected paraffin-section image supports the antibody’s IHC use under its stated retrieval and detection conditions, while its fixative remains unreported (datasheet A00672).

Boster reagents

Best CYP2E1 / Cytochrome P450 2E1 IHC Antibodies

A00672 has IHC images from human liver cancer and mouse liver paraffin sections (catalog image captions); both antibodies list human, mouse, and rat reactivity (catalog reactivity). No IF/ICC data are supplied (catalog applications/images).

Real IHC data

Anti-Cytochrome P450 2E1/CYP2E1 Antibody ®

Cat # A00672

View product →

A00672 lists IHC for human, mouse, and rat, with images from human liver cancer and mouse liver paraffin sections (catalog applications/reactivity; image captions). M00672 lists IHC for human, mouse, and rat, but supplies no IHC image or tissue validation (catalog applications/reactivity; image data).

Which to pick: For tissue IHC, choose A00672 when a documented paraffin-section example is useful; its captions report citrate retrieval and 1 μg/ml primary antibody, but do not report the fixative (A00672 image captions). Neither SKU lists IF/ICC validation, so there is no evidence-based IF/ICC pick here (catalog applications/images). For cross-species IHC, both list human, mouse, and rat reactivity; M00672 is rabbit monoclonal clone AADC-3, while A00672 has the documented human and mouse paraffin-section images (catalog reactivity/clone; 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.