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FABP5 / Fatty acid-binding protein 5 · IHC design guide
Design Immunohistochemistry for FABP5
Plan FABP5 chromogenic IHC on paraffin sections using the catalog antibody at 0.5–1 μg/ml (datasheet PA1475). Assess cytoplasmic and nuclear staining in cervical or esophageal squamous epithelium, where staining is high, alongside adipocytes, where staining is not detected (HPA tissue IHC).
Evidence assembled Sep 2026 · For research use; verify linked source records and product datasheet before use
FABP5 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 | Cytoplasmic and nuclear in squamous epithelia (HPA tissue IHC) | |
| Staining pattern | Squamous and endothelial cells: cytoplasmic and nuclear staining (HPA tissue IHC) | |
| Antigen retrieval | Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen) | |
| Positive control | Cervix+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Avoid prolonged formalin fixation that may mask epitopes (standard IHC practice) | |
| Caveat | Ligand binding can shift FABP5 staining toward nuclei (UniProt) | |
| Regulation | Highly expressed in psoriatic skin (UniProt) | |
| Isoform / epitope | No annotated isoforms; mature chain spans residues 2–135 (UniProt) |
Section 1
Recommended FABP5 IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol with four published FABP5 paraffin-section protocols (PMC3251696; PMC11039673; PMC8477672; PMC3551956).
| Sample | FFPE tissue sections (standard) |
| Fixation | 10% neutral-buffered formalin, 24 h, standard processing (standard) |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in Tris-EDTA buffer, pH 9.0, 20 min at 95–98 °C (standard rule: nuclear antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit anti-FABP5, 0.5-1μg/ml (datasheet PA1475) |
| Primary incubation | Overnight at 4 °C (standard) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FABP5-positive staining in squamous epithelial cells of cervix (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic and nuclear expression in squamous epithelia and endothelial cells. No signal in the no-primary control. |
💡Decision noteStart with Tris-EDTA HIER at pH 9.0, 95–98 °C for 20 min (page retrieval); published alternatives use citrate at pH 6.0 (PMC3251696; PMC3551956).
Section 2
What Is the Expected FABP5 Staining Pattern?
FABP5 should stain mainly in the cytoplasm, with possible nuclear staining (UniProt Q01469; HPA: Enhanced IHC). Expect strong staining in squamous epithelial cells of cervix, esophagus, oral mucosa, and vagina (HPA: High). FABP5 has no transmembrane segment (UniProt Q01469 topology).
| Strong cytoplasmic staining in squamous epithelium | Expected in cervix, esophagus, oral mucosa, or vagina (HPA: High). |
| Cytoplasmic staining with some nuclear staining | Consistent with FABP5 localization (UniProt Q01469; HPA: tissue IHC). |
| Predominantly extracellular staining | Suspect an IHC artifact; intracellular staining is expected (UniProt Q01469; HPA: tissue IHC). |
| Strong staining in adipocytes | Check cross-reactivity or detection activity (HPA: adipocytes not detected). |
| Diffuse staining across the section | Check blocking and detection background (standard IHC practice). |
💡Expected FABP5 appearanceA positive result is strong, mainly cytoplasmic squamous epithelial staining, with possible nuclear signal; strong adipocyte staining is suspect (HPA: High in squamous cells; adipocytes not detected; UniProt Q01469).
| Fixation and cross-linking | Excess fixation can mask epitopes and weaken IHC signal (standard IHC practice). |
| Antigen retrieval | Retrieval conditions can change signal and background in paraffin sections (standard IHC practice). |
| Intracellular localization | Assess cytoplasm and nucleus; FABP5 has no transmembrane segment (UniProt Q01469). |
| Endogenous peroxidase | Residual activity can produce chromogenic background; include a detection control (standard IHC practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in positive squamous epithelium | Epitope masking or weak detection (standard IHC practice). | Adjust retrieval and verify detection on cervix or esophagus (HPA: High). |
| Strong extracellular staining | Possible section or detection artifact (standard IHC practice). | Inspect morphology and a no-primary control (standard IHC practice). |
| Adipocytes stain strongly | Possible cross-reactivity or detection activity (HPA: adipocytes not detected). | Compare a no-primary control and known-positive tissue (standard IHC practice). |
| Diffuse chromogenic background | Inadequate blocking or residual peroxidase (standard IHC practice). | Check blocking, peroxidase quenching, and no-primary control (standard IHC practice). |
| Nuclear signal accompanies cytoplasmic signal | Ligand-dependent nuclear transport is reported (UniProt Q01469). | Score both compartments and compare cell types (UniProt Q01469; HPA: tissue IHC). |
| What should IF/ICC show? | FABP5 is mainly cytosolic (HPA: supported ICC-IF). | Expect cytosol, with possible plasma membrane signal (HPA: approved ICC-IF). |
Experiment evidence
IHC & IF images showing FABP5 staining
PA1475 · IHCAnti-Fatty Acid Binding Protein 5 antibody, PA1475, IHC(P) IHC(P): Human Intestinal Cancer Tissue
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000164687-FABP5/tissue/cerebral+cortex#imid_15676695
HPA · EsophagusHuman Protein Atlas IHC, Esophagus. Source: https://www.proteinatlas.org/ENSG00000164687-FABP5/tissue/esophagus#imid_15676683
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000164687-FABP5/tissue/colon#imid_15673901
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000164687-FABP5/tissue/liver#imid_15673902
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB040577; green = FABP5, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB040577; green = FABP5, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FABP5 IHC & IF
🧪Run esophagus first: its squamous epithelial cells should stain for FABP5 (HPA: High in esophageal squamous epithelial cells). Use adipose tissue as the negative tissue, focusing on adipocytes (HPA: Not detected in adipocytes); on the esophagus slide, non-squamous cells should serve as an internal background comparator rather than be scored as positive squamous epithelium (HPA: High in squamous epithelial cells).
Positive control tissue: Cervix (Squamous epithelial cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FABP5 in A-431, U2OS, with annotated localisation: Cytosol (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a host- and isotype-matched control for a monoclonal primary, or matched nonimmune host IgG for a polyclonal primary (standard IHC practice); use FABP5 knockout material, if available, or an immunizing-peptide block to assess specificity (standard IHC practice). Quench endogenous peroxidase for chromogenic detection and check the esophageal section for background staining (standard IHC practice).
⚠️Feasibility: Start with consistently fixed, neutral-buffered-formalin paraffin sections and pilot a 6–24 hour fixation window; optimize heat-induced antigen retrieval for the catalog antibody because no retrieval condition is supplied here (standard IHC practice). Frozen sections can avoid heat retrieval, but paraffin sections offer a practical first readout of the esophageal squamous layers; IF has its own guide (standard IHC/IF practice). Score intact epithelium and exclude folded or detached squamous tissue that can concentrate apparent chromogenic signal (standard IHC practice).
HPA tissue IHC evidence for FABP5
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. Antibody staining in cells/structures not annotated, view images.). 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 |
|---|---|---|---|---|
| Cervix | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Esophagus | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Lung | Alveolar cells type II | High | Protein (IHC) | HPA → |
| Oral mucosa | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Skin | Cells in corneal layer | 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 → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced FABP5 IHC Tips
Troubleshoot FABP5 staining in paraffin sections by checking retrieval, compartment, cell identity, controls, and scoring before interpreting changes in signal.
How should I troubleshoot weak FABP5 staining after antigen retrieval?
For FABP5 paraffin IHC, start with Tris-EDTA pH 9.0 HIER at 95–98 °C for 20 min (page retrieval rule: nuclear antigen). If signal is weak, verify that sections reached the intended temperature, cooled in retrieval buffer, and remained attached through washing (standard IHC practice). Compare a fresh section with a known positive squamous epithelium section in the same run; cervix and esophagus show high staining in squamous epithelial cells (HPA: tissue IHC). If high-pH retrieval damages morphology, test citrate pH 6.0 as a fallback while keeping detection conditions constant (standard IHC practice). Score cytoplasmic and nuclear signal separately because FABP5 can occupy both compartments (UniProt Q01469: subcellular location).
Could fixation explain weak or uneven FABP5 staining in paraffin sections?
Compare sections with documented fixation histories before changing antibody concentration, because fixation and processing can alter epitope access and morphology (standard IHC practice). Underfixation may leave fragile tissue with patchy staining, whereas prolonged formalin fixation can increase crosslinking and weaken staining after retrieval (standard IHC practice). Keep section thickness, retrieval, and chromogen development consistent across the comparison, and include an internal positive area when available (standard IHC practice). Evaluate squamous epithelial cytoplasm and nuclei separately: FABP5 is primarily cytoplasmic but can move into the nucleus after certain ligand binding (UniProt Q01469: subcellular location). A positive control with strong squamous epithelial staining helps distinguish a processing problem from low target abundance (HPA: cervix and esophagus, high).
Is nuclear FABP5 staining plausible when cytoplasmic staining is stronger?
Yes: FABP5 is primarily cytoplasmic, and binding certain ligands can expose a nuclear localization motif and promote nuclear transport (UniProt Q01469: subcellular location). HPA describes cytoplasmic and nuclear staining in squamous epithelia and endothelial cells, so record those compartments independently in paraffin sections (HPA: tissue IHC profile). Predominantly cytosolic signal is also consistent with the supported subcellular assignment; plasma membrane localization is listed as an additional location (HPA: subcellular). Check whether nuclear color sits within intact counterstained nuclei and whether adjacent cytoplasm is interpretable, using the same chromogen exposure across sections (standard IHC practice). Diffuse color over tissue folds or damaged edges needs repeat evaluation before it is assigned to either compartment (standard IHC practice).
How can I assess whether an unexpected staining pattern reflects the FABP5 epitope?
Review the catalog antibody’s stated immunogen and validation for paraffin IHC before attributing an unexpected pattern to FABP5 (standard IHC practice). The supplied FABP5 record lists 0 isoforms, no transmembrane segment, and no annotated glycosylation sites, so those features do not explain a membrane restricted or glycan dependent staining pattern (UniProt Q01469: isoforms, topology, glycosylation). Reported modifications include acetylation at residues 2 and 17 and phosphorylation at residue 131; their effect on this antibody cannot be inferred without its epitope information (UniProt Q01469: modified residues). Compare retrieval conditions and staining in a documented positive section before interpreting altered epitope accessibility (standard IHC practice). Retain no-primary controls to assess detection-related color (standard IHC practice).
How should I compare FABP5 paraffin IHC with multiplex IF staining?
Use the chromogenic paraffin section to establish cell type and compartment before comparing it with a separate IF experiment (standard IHC/IF practice). For multiplex IF, pair FABP5 with a validated marker of the expected cell type, such as a squamous epithelial marker in cervix or esophagus, where HPA reports high FABP5 staining (HPA: tissue IHC). Select fluorophores after checking tissue autofluorescence, and use single color controls to distinguish channel bleed-through from colocalization (standard IF practice). Because FABP5 has no transmembrane segment and is mainly cytosolic, permeabilize for intracellular epitope access while preserving nuclear boundaries (UniProt Q01469: topology; HPA: subcellular; standard IF practice). Compare compartment patterns, since fluorescent intensity and DAB intensity are measured differently (standard IHC/IF practice).
What should I check when FABP5 DAB staining appears diffuse?
Run no-primary and detection-only controls to identify color caused by the detection system rather than antibody binding (standard IHC practice). Quench endogenous peroxidase before horseradish peroxidase detection, then compare controlled DAB development times and wash stringency across sections (standard IHC practice). Inspect folds, cut edges, pigment, and necrotic areas at the same magnification as intact tissue before calling diffuse color positive (standard IHC practice). FABP5 is mainly cytosolic, with nuclear localization possible under certain ligand conditions, so a uniform deposit outside recognizable cells needs scrutiny (HPA: subcellular; UniProt Q01469: subcellular location). If background persists, optimize blocking and antibody concentration using the catalog antibody’s stated IHC range, without sacrificing positive control staining (standard IHC practice).
How should I score FABP5 when both cytoplasmic and nuclear staining vary? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, then report cytoplasmic and nuclear results separately (standard IHC practice; UniProt Q01469: subcellular location). For a defined epithelial region, an H-score can combine staining intensity 0–3 with the percentage of cells at each intensity; also report the percentage of positive cells (standard IHC practice). Normalize each percentage to the number of evaluable cells in that region, excluding folds and necrosis by the same rule for every section (standard IHC practice). For spatial cell counts, report positive cells per mm² of evaluable tissue and state the region sampled (standard IHC practice). Keep scoring thresholds fixed across cases and use a same-run positive control to monitor staining drift (standard IHC practice).
How can I distinguish true FABP5 staining from artefact?
First confirm that color is associated with intact cells and a plausible compartment: FABP5 is mainly cytoplasmic, with possible nuclear localization (UniProt Q01469: subcellular location). Strong staining in squamous epithelial cells is plausible in cervix, esophagus, oral mucosa, and vagina, whereas HPA reports no detection in bronchial respiratory epithelial cells (HPA: tissue IHC). Treat staining confined to cut edges, folds, or necrotic regions as suspect until it recurs in intact tissue (standard IHC practice). Compare no-primary and peroxidase controls to identify nonspecific DAB deposition or endogenous enzyme activity (standard IHC practice). Interpret discrepancies cautiously because HPA rates tissue IHC reliability as Enhanced with medium consistency between staining and RNA expression data (HPA: tissue IHC reliability).
Boster reagents
Best FABP5 / Fatty acid-binding protein 5 IHC Antibodies
PA1475 has a human paraffin-section IHC image from intestinal cancer tissue (catalog: IHC application and human reactivity; image alt: human intestinal cancer tissue).
Real IHC data
Anti-Fatty Acid Binding Protein 5/FABP5 Antibody ®
Cat # PA1475
PA1475 is listed for human IHC (catalog: applications and reactivity). Its IHC-P figure shows human intestinal cancer tissue (image alt: human intestinal cancer tissue).
Which to pick: Choose PA1475 for human FFPE IHC; its catalog IHC dilution is 0.5–1 μg/ml (catalog: IHC application and human reactivity; datasheet: 0.5–1 μg/ml). No listed SKU has IF/ICC validation or nonhuman reactivity, so this payload supports neither an IF/ICC nor a cross-species recommendation (catalog: applications and reactivity).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q01469 (FABP5_HUMAN, Fatty acid-binding protein 5).
- Human Protein Atlas. FABP5 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. FABP5 subcellular location (ICC-IF): Mainly localized to the cytosol. In addition localized to the plasma membrane..
- Human Protein Atlas. FABP5 antibody validation summary (3 antibodies).
- Molecular determinants of retinoic acid sensitivity in pancreatic cancer. Clinical cancer research : an official journal of the American Association for Cancer Research 2012 — PMC3251696.
- Fatty acid-binding protein 5 is a functional biomarker and indicator of ferroptosis in cerebral hypoxia. Cell death & disease 2024 — PMC11039673.
- Expression and function analysis of CRABP2 and FABP5, and their ratio in esophageal squamous cell carcinoma. Open medicine (Warsaw, Poland) 2021 — PMC8477672.
- Cigarette smoke decreases airway epithelial FABP5 expression and promotes Pseudomonas aeruginosa infection. PloS one 2013 — PMC3551956.
- PubMed PMID:1512466 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FABP5 (Fatty acid-binding protein 5). Expected localisation Cytoplasmic and nuclear in squamous epithelia (HPA tissue IHC). Antigen retrieval: Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen). Validated IHC antibody: PA1475 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Cervix (Squamous epithelial cells); negative Adipose tissue. Protocol steps: 1. Sample: FFPE tissue sections (standard); 2. Fixation: 10% neutral-buffered formalin, 24 h , standard processing (standard); 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat-induced epitope retrieval in Tris-EDTA buffer, pH 9.0 , 20 min at 95–98 °C (standard rule: nuclear antige; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-FABP5, 0.5-1μg/ml (datasheet PA1475); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Avoid prolonged formalin fixation that may mask epitopes (standard IHC practice); Caveat: Ligand binding can shift FABP5 staining toward nuclei (UniProt); Isoform / epitope: No annotated isoforms; mature chain spans residues 2–135 (UniProt); Regulation: Highly expressed in psoriatic skin (UniProt). Evidence: UniProt Q01469, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the cytosol. In addi, Datasheet PA1475, PMC3251696, PMC11039673. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FABP5/immunohistochemistry-ihc-guide.