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FABP6 / Gastrotropin · IHC design guide
Design Immunohistochemistry for FABP6
Plan FABP6 IHC in paraffin sections using small-intestinal endocrine cells as a positive tissue reference (HPA tissue IHC). This guide covers fixation, chromogenic staining, controls, and interpretation of cytoplasmic and membranous staining (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FABP6 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 membranous staining (HPA tissue IHC) | |
| Staining pattern | High in small-intestinal endocrine cells; cytoplasmic/membranous (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A07132) | |
| Positive control | Small intestine | |
| 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). Selected-image fixative and duration unreported (datasheet A07132); verify before use. | |
| Caveat | Appendix endocrine cells are undetected (HPA tissue IHC) | |
| Regulation | Intestine-enriched expression (HPA RNA) | |
| Isoform / epitope | 2 isoforms differ in gut distribution; epitope coverage unknown (UniProt) |
Section 1
Recommended FABP6 IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet A07132) is accompanied by published FABP6 protocols for human colorectal tissue (PMC6814121), mouse ovary (PMC4498371), and human prostate tissue (PMC5347732).
| Sample | Paraffin-embedded human rectal cancer tissue; fixative not specified (datasheet A07132) |
| Fixation | Image fixative and duration unreported (datasheet A07132); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A07132); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A07132) |
| Primary antibody | Rabbit anti-FABP6, 0.5-1μg/ml (datasheet A07132) |
| Primary incubation | Overnight at 4 °C (datasheet A07132) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A07132) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FABP6-positive staining in endocrine cells of small intestine (HPA tissue IHC: High). HPA tissue profile: Distinct cytoplasmic and membranous expression in small intestine. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval (datasheet A07132; PMC6814121), then optimize primary antibody incubation for the chosen tissue.
Section 2
What Is the Expected FABP6 Staining Pattern?
FABP6 staining is expected in the cytoplasm and along cell membranes of the small intestine, with high staining reported in endocrine cells (HPA: tissue IHC, Enhanced reliability). UniProt also places FABP6 near the nucleus on the apical side of normal and neoplastic cells; it has no transmembrane segment (UniProt P51161: subcellular location and topology).
| Distinct cytoplasmic staining, with membrane-associated signal, in small-intestinal endocrine cells. | This matches the reported compartment pattern and high cell-level staining (HPA: small-intestine IHC). Compare cell identity and distribution with the counterstained tissue architecture (general IHC practice). |
| Signal is predominantly nuclear, with little cytoplasmic or membrane-associated staining. | A predominantly nuclear pattern does not match the reported locations (HPA: tissue IHC; UniProt P51161: subcellular location). Treat it as suspect; inspect morphology and control sections before assigning it to FABP6 (general IHC practice). |
| Strong staining appears in adipocytes or adrenal glandular cells. | Those specific cell populations were not detected by HPA tissue IHC (HPA: adipose tissue and adrenal gland). Check for nonspecific antibody binding or endogenous chromogenic activity; a positive cell elsewhere in either tissue cannot be judged from these entries alone (general IHC practice). |
| Color spreads across the section without a clear cellular pattern. | Diffuse deposition does not reproduce the distinct cytoplasmic and membranous pattern (HPA: small-intestine IHC). Check background on the no-primary control, then review blocking, washes and detection conditions (general IHC practice). |
| No convincing staining appears in a small-intestine section with identifiable endocrine cells. | This conflicts with the reported high staining in those cells (HPA: small-intestine IHC). First confirm tissue and cell identification, then assess the antibody and detection run with appropriate controls (general IHC practice). |
💡Expected FABP6 appearanceCall a section positive when small-intestinal endocrine cells show high, distinct cytoplasmic and membrane-associated staining (HPA: small-intestine IHC); predominantly nuclear color or diffuse section-wide color is suspect against that pattern (HPA: tissue IHC; UniProt P51161: subcellular location).
| Compartment and topology | FABP6 is annotated in cytoplasm and at membranes, with no transmembrane segment (UniProt P51161). Interpret membrane-associated color alongside the cytoplasmic pattern; it does not establish a membrane-spanning protein (UniProt P51161: topology). |
| Tissue and cell selection | HPA reports high staining in small-intestinal endocrine cells and no detection in specified adipocytes or adrenal glandular cells (HPA: tissue IHC). These observations guide positive and negative comparisons, without defining every cell in those tissues. |
| Isoform coverage | UniProt lists 2 isoforms with different intestinal distributions, and reports isoform 2 in colorectal adenocarcinomas and adjacent normal mucosa (UniProt P51161: tissue specificity). No supplied antibody epitope establishes which isoform the IHC stain detects. |
| Antibody validation | HPA labels the tissue pattern Enhanced and lists 2 antibodies with Enhanced IHC status, HPA012601 and CAB024713 (HPA: tissue IHC and antibodies). This supports the reported pattern; it does not establish performance under every local staining condition. |
| Processing and retrieval evidence | UniProt lists no signal peptide or propeptide and annotates a Gastrotropin chain spanning residues 2–128 (UniProt P51161: processing). The supplied sources give no FABP6-specific retrieval response or fixation sensitivity, so assess those conditions with controls (general IHC practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| The expected small-intestine signal is absent or weak. | Possible causes include incorrect tissue or cell identification, an ineffective detection run, or unsuitable local IHC conditions (general IHC practice). The expected endocrine-cell level is high (HPA: small-intestine IHC). | Verify the section and endocrine-cell morphology; inspect a run control, then optimize retrieval and antibody conditions using the IHC-validated antibody's instructions (general IHC practice). Do not infer a FABP6-specific fixation effect from this result. |
| Adipocytes or adrenal glandular cells stain strongly. | HPA reports those cell populations as not detected (HPA: tissue IHC). Nonspecific binding or endogenous detection activity can produce misleading chromogenic color (general IHC practice). | Compare no-primary and detection controls; review blocking and chromogen development, then repeat with a validated antibody if needed (general IHC practice). Score the named cell population rather than treating the whole tissue as negative (HPA: tissue IHC). |
| Color appears mainly in nuclei. | Nuclear dominance conflicts with the cytoplasmic and membrane-associated locations (HPA: tissue IHC; UniProt P51161: subcellular location). Counterstain or precipitate can also complicate compartment calls (general IHC practice). | Inspect cellular boundaries and the no-primary control; adjust detection or counterstain conditions if they obscure the cytoplasm (general IHC practice). Require a reproducible expected pattern before scoring FABP6 positive (HPA: tissue IHC). |
| Background obscures the distinct cellular pattern. | Diffuse color may arise from nonspecific binding, incomplete washes or detection background (general IHC practice); it prevents assessment of the reported pattern (HPA: small-intestine IHC). | Inspect no-primary and negative-cell controls; review blocking, wash steps and development time (general IHC practice). Reassess only where cytoplasmic and membrane-associated staining is separable from background (HPA: tissue IHC). |
| Staining varies between intestinal regions or a tumor and adjacent mucosa. | UniProt reports different distributions for isoforms 1 and 2, including isoform 2 in colorectal adenocarcinomas and adjacent mucosa (UniProt P51161: tissue specificity). The supplied IHC data do not resolve isoforms. | Record region, morphology and compartment for each area; compare like cell populations before interpreting differences (general IHC practice). Do not assign an isoform from this IHC pattern without isoform-specific antibody evidence. |
| Can this pattern be used as an IF/ICC readout? | HPA supplies no main ICC-IF location and no cell-line ICC-IF images for FABP6 (HPA: subcellular record). Its Enhanced validation entries concern IHC (HPA: antibodies). | Use the cytoplasmic and membrane-associated locations as a hypothesis (UniProt P51161; HPA: tissue IHC). Establish an IF/ICC pattern with appropriate controls in the separate IF/ICC guide (general IF practice). |
Experiment evidence
IHC & IF images showing FABP6 staining
A07132 · IHCIHC analysis of FABP6 using anti-FABP6 antibody (A07132). FABP6 was detected in paraffin-embedded section of human rectal cancer tissue. Hea
A07132 · IHCIHC analysis of FABP6 using anti-FABP6 antibody (A07132). FABP6 was detected in paraffin-embedded section of human rectal cancer tissue. Hea
PA2158 · IHCAnti-FABP6 antibody, PA2158, IHC(P) IHC(P): Human Lung Cancer Tissue
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000170231-FABP6/tissue/cerebral+cortex#imid_6925744
HPA · Small intestineHuman Protein Atlas IHC, Small intestine. Source: https://www.proteinatlas.org/ENSG00000170231-FABP6/tissue/small+intestine#imid_6925629
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000170231-FABP6/tissue/colon#imid_6925654
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000170231-FABP6/tissue/liver#imid_6925671
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FABP6 IHC & IF
🧪Run small intestine first: endocrine cells should stain strongly (HPA: High in small-intestine endocrine cells). Use appendix endocrine cells as a negative tissue (HPA: Not detected in appendix endocrine cells); neighboring cells on the positive slide should provide a background reference, with any staining interpreted by cell type rather than assumed absent.
Positive control tissue: Small intestine (Endocrine cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for FABP6; derive a cell-line control from the positive tissue's cell type (Endocrine cells) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary, secondary-only control and a rabbit isotype control matched to the primary antibody’s class and concentration (caption: rabbit anti-FABP6 primary). Use FABP6-knockout material as a biological negative; for the caption’s SABC/DAB method, quench endogenous peroxidase and assess endogenous biotin signal (caption: biotinylated secondary, SABC and DAB).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the fixative used for the A07132 paraffin section is unreported (caption: fixative not stated). The demonstrated paraffin-section workflow used heat-mediated EDTA retrieval at pH 8.0; whether FABP6 staining depends on that retrieval is unreported (caption: EDTA retrieval). There is insufficient matched evidence to judge frozen sections or IF/ICC easier; with SABC/DAB in small intestine, check for endogenous biotin and peroxidase background (caption: SABC/DAB; standard IHC practice).
HPA tissue IHC evidence for FABP6
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 |
|---|---|---|---|---|
| Small intestine | Endocrine cells | 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 | Endocrine 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 FABP6 IHC Tips
Troubleshoot FABP6 staining in paraffin sections by checking retrieval, cellular pattern, controls and scoring against the available tissue evidence.
What retrieval should I start with for weak FABP6 staining in paraffin sections?
Start with heat-mediated retrieval in EDTA at pH 8.0 (datasheet A07132). The selected paraffin-section image used that retrieval before FABP6 staining in human rectal cancer tissue (datasheet A07132). Keep section thickness, heating time and cooling time consistent across the staining run, then compare a weak section with a concurrently processed positive control. Small intestine provides a useful control because FABP6 shows distinct cytoplasmic and membranous staining there (HPA tissue IHC). If signal remains weak, assess retrieval heating and antibody incubation before testing a different buffer; any alternative retrieval condition needs its own control comparison.
Can fixation explain weak or patchy FABP6 staining?
Target-specific sensitivity to fixation is unknown: the selected A07132 paraffin-section caption does not state a fixative (datasheet A07132). Record the fixative, fixation duration and processing history for each block before comparing staining intensity across specimens. For a troubleshooting comparison, stain sections from differently processed blocks in one run with the same EDTA pH 8.0 retrieval (datasheet A07132). Include a control with the expected small-intestinal cytoplasmic and membranous pattern (HPA tissue IHC). If results vary with processing history, report that association without attributing it specifically to a FABP6 epitope or modification.
Where should convincing FABP6 staining appear within positive cells?
Look primarily for cytoplasmic staining with a possible membranous component: both occur in small intestine (HPA tissue IHC). FABP6 has also been described close to the nucleus on the apical side of normal and neoplastic cells (UniProt P51161 subcellular location). Interpret a membrane-like rim alongside cytoplasmic signal, since FABP6 has no transmembrane segment (UniProt P51161 topology). Compare the apparent compartment with nearby negative cells on the same section, and inspect whether staining follows cell boundaries or cut edges. An isolated nuclear pattern conflicts with the reported localisation and warrants review of morphology, background and controls (UniProt P51161 subcellular location).
Could isoforms or epitope placement change which bowel regions stain?
Yes: FABP6 has 2 annotated isoforms with different reported intestinal distributions (UniProt P51161 isoforms and tissue specificity). Isoform 1 is reported in jejunum, ileum, cecum and ascending colon; isoform 2 extends through additional bowel regions and rectum (UniProt P51161 tissue specificity). Isoform 2 is also reported at protein level in colorectal adenocarcinomas and adjacent normal mucosa (UniProt P51161 tissue specificity). The supplied evidence does not identify the catalog antibody's epitope, so do not assign an isoform from staining alone. If regional differences matter, verify epitope coverage independently and compare sections under identical retrieval and detection conditions.
How should I investigate FABP6 by multiplex immunofluorescence?
Treat IF optimisation as separate from this paraffin-section chromogenic workflow; the supplied subcellular record lists no ICC/IF images (HPA subcellular). Multiplex FABP6 with a validated marker for the expected endocrine cells, which show high small-intestinal FABP6 staining by tissue IHC (HPA tissue IHC). Choose fluorophores after checking unstained-tissue autofluorescence, and place the weaker signal in a cleaner spectral channel. Assess permeabilisation for access to cytoplasmic FABP6 and the cytoplasmic side of membrane-associated signal; no transmembrane segment is annotated (UniProt P51161 topology and subcellular location). Include single-stain and secondary-only controls to distinguish signal from spectral spillover and background.
What should I check when FABP6 DAB staining looks diffuse?
First inspect an unstained or reagent-control section for pigment and endogenous peroxidase activity before assigning diffuse brown signal to FABP6. The selected caption used 10% goat serum block, 1 μg/ml primary antibody overnight at 4°C, and biotin-based detection with DAB (datasheet A07132). Check whether excess primary or detection reagent raises staining in cells expected to be negative, using the same development time across controls. Adipocytes in adipose tissue were not detected in the supplied tissue profile (HPA tissue IHC). Interpret a diffuse signal cautiously if it lacks the reported cytoplasmic or membranous pattern (HPA tissue IHC).
How should I quantify FABP6 across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and tissue region before scoring, then record both the percentage of positive cells and staining intensity. An H-score can combine the percentage at each intensity grade into a 0–300 score; report the scoring rules and sampled area. For spatial comparisons, count positive cells per mm² of viable, evaluable tissue, or normalise positive cells to all cells of the same annotated type. Keep retrieval, chromogen development and imaging settings consistent across the comparison. Report cytoplasmic and membranous staining separately when feasible, because both are described in small intestine (HPA tissue IHC).
How can I distinguish true FABP6 staining from artefact?
Give greatest weight to a reproducible cytoplasmic or membranous pattern in the expected cells: small-intestinal endocrine cells show high staining in the supplied profile (HPA tissue IHC). An apical, near-nuclear distribution can also fit the reported localisation (UniProt P51161 subcellular location). Compare suspicious signal with negative tissue areas and reagent controls, especially where section edges, necrosis, pigment or endogenous enzyme activity can mimic chromogenic staining. Isolated nuclear staining warrants scrutiny because the supplied localisation is cytoplasmic and membranous (UniProt P51161 subcellular location; HPA tissue IHC). Interpret rectal cancer staining alongside morphology and controls; the selected A07132 image demonstrates staining in a paraffin section of that tissue (datasheet A07132).
Boster reagents
Best FABP6 / Gastrotropin IHC Antibodies
Two anti-FABP6 antibodies have IHC images: A07132 in paraffin sections of human rectal cancer and rat intestine, and PA2158 in human lung cancer tissue (catalog image captions).
Real IHC data
Anti-FABP6 Antibody ®
Cat # A07132
Real IHC data
Anti-Gastrotropin FABP6 Antibody ®
Cat # PA2158
A07132 lists IHC and human, mouse, and rat reactivity; its images show paraffin-section staining in human rectal cancer and rat intestine (catalog applications, reactivity, and image captions). PA2158 lists human IHC and has an IHC(P) image of human lung cancer tissue (catalog applications, reactivity, and image caption).
Which to pick: For human tissue IHC, A07132 has a documented paraffin-section protocol, while PA2158 has a human lung cancer IHC(P) image (A07132 and PA2158 image captions). For work across species, choose A07132: it lists human, mouse, and rat reactivity, with IHC images for human and rat tissue (A07132 catalog reactivity and image captions). Neither SKU lists IF/ICC validation or clonality, so neither has a supported IF/ICC recommendation; the IHC captions do not report the fixative (catalog applications, clone fields, and image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P51161 (FABP6_HUMAN, Gastrotropin).
- Human Protein Atlas. FABP6 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. FABP6 subcellular location (ICC-IF): Highest expression in EFO-21: 20.7 nTPM.
- Human Protein Atlas. FABP6 antibody validation summary (2 antibodies).
- High expression of FABP4 and FABP6 in patients with colorectal cancer. World journal of surgical oncology 2019 — PMC6814121.
- The fatty acid binding protein 6 gene (Fabp6) is expressed in murine granulosa cells and is involved in ovulatory response to superstimulation. The Journal of reproduction and development 2015 — PMC4498371.
- The increased expression of fatty acid-binding protein 9 in prostate cancer and its prognostic significance. Oncotarget 2016 — PMC5347732.
- In vitro patterning of pluripotent stem cell-derived intestine recapitulates in vivo human development. Development (Cambridge, England) 2017 — PMC5358103.
- PubMed PMID:7619861 — UniProt-cited evidence.
- PubMed PMID:7588781 — UniProt-cited evidence.
- PubMed PMID:17909007 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FABP6 (Gastrotropin). Expected localisation Cytoplasmic and membranous staining (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A07132). Validated IHC antibody: A07132 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Small intestine (Endocrine cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human rectal cancer tissue; fixative not specified (datasheet A07132); 2. Fixation: Image fixative and duration unreported (datasheet A07132); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat retrieval: EDTA pH 8.0 (datasheet A07132); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A07132); 8. Primary antibody: Rabbit anti-FABP6, 0.5-1μg/ml (datasheet A07132); 9. Primary incubation: Overnight at 4 °C (datasheet A07132). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific). Selected-image fixative and duration unreported (datasheet A07132); verify before use.; Caveat: Appendix endocrine cells are undetected (HPA tissue IHC); Isoform / epitope: 2 isoforms differ in gut distribution; epitope coverage unknown (UniProt); Regulation: Intestine-enriched expression (HPA RNA). Evidence: UniProt P51161, HPA tissue IHC · Enhanced, HPA cell-line RNA · Highest expression in EFO-21: 20.7 nTPM, Datasheet A07132, PMC6814121, PMC4498371. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FABP6/immunohistochemistry-ihc-guide.