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FGF1 / Fibroblast growth factor 1 · IHC design guide
Design Immunohistochemistry for FGF1
Plan FGF1 chromogenic IHC in paraffin sections around the selective endothelial cytoplasmic pattern reported in tissue (HPA tissue IHC). This guide covers fixation consistency, interpretation of secreted FGF1, and epitope uncertainty across 2 isoforms (standard IHC practice; UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FGF1 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 | Endothelial cytoplasm (HPA tissue IHC) | |
| Staining pattern | Selective cytoplasmic staining in endothelial cells (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet PB9944) | |
| Positive control | Kidney | |
| 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 | Secretion may separate FGF1 staining from its source cells (UniProt) | |
| Regulation | Expression regulation not established (UniProt) | |
| Isoform / epitope | 2 isoforms; antibody epitope coverage is unknown (UniProt) |
Section 1
Recommended FGF1 IHC & IF Protocols
The catalog antibody’s paraffin IHC protocol (datasheet: PB9944) is followed by published FGF1 IHC protocols for rat brain sections (PMC1831852) and gastric adenocarcinoma (PMC4360790).
| Sample | Paraffin-embedded mouse intestine tissue; fixative not specified (datasheet PB9944) |
| Fixation | Image fixative and duration unreported (datasheet PB9944); 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 PB9944); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet PB9944) |
| Primary antibody | Rabbit anti-FGF1, 0.5-1μg/ml (datasheet PB9944) |
| Primary incubation | Overnight at 4 °C (datasheet PB9944) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet PB9944) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FGF1-positive staining in cells in glomeruli of kidney (HPA tissue IHC: High). HPA tissue profile: Highly selective cytoplasmic expression in endothelial cells. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA retrieval at pH 8.0 (datasheet: PB9944); citrate at pH 6.0 is a published alternative for gastric sections (PMC4360790).
Section 2
What Is the Expected FGF1 Staining Pattern?
FGF1 can occupy the cytoplasm, cell cortex, cytosol and nucleus, and can be secreted without a cleavable signal sequence (UniProt P05230). For paraffin-section IHC, expect selective cytoplasmic staining associated with endothelial cells (HPA: tissue IHC profile). Kidney glomerular cells provide a reported high-staining reference, although HPA does not identify every positive glomerular cell subtype (HPA: kidney, High). HPA rates its tissue IHC evidence Enhanced and notes medium agreement between staining and RNA expression (HPA: reliability description).
| Selective cytoplasmic chromogen in endothelial cells, with strong staining in cells of kidney glomeruli (HPA: tissue IHC profile; kidney, High). | This matches the reported tissue pattern. Identify the stained cell type from tissue morphology before assigning it to endothelium; the kidney entry names glomerular cells without resolving every subtype (HPA: tissue IHC profile; kidney, High). |
| Predominantly nuclear staining in a paraffin section, with little of the reported endothelial cytoplasmic pattern (HPA: tissue IHC profile). | Treat the mismatch as a pattern needing review, rather than proof of an artefact: UniProt includes nuclear FGF1, and HPA reports supported nucleoplasmic ICC-IF localization (UniProt P05230; HPA: subcellular ICC-IF). Check morphology and controls before interpreting the IHC result (general IHC practice). |
| Strong chromogen in adipocytes or respiratory epithelial cells, where HPA reports no detection (HPA: adipose tissue; bronchus). | These are unexpected cell-type results for the cited tissue entries. Check whether staining follows recognizable cells and whether controls show background; cross-reactivity or endogenous detection activity are possible explanations, not diagnoses from the slide alone (HPA: tissue IHC; general IHC practice). |
| Diffuse chromogen across cells and cell-free areas, without a selective cellular pattern (HPA: tissue IHC profile). | This does not reproduce HPA's highly selective cytoplasmic profile. Inspect the negative control and detection reagents for background, then reassess antibody concentration and wash conditions as general IHC variables (HPA: tissue IHC profile; general IHC practice). |
| No visible staining in kidney glomerular cells used as a positive reference (HPA: kidney, High). | A negative reference section leaves the run uninterpretable for tissue negatives. Verify that the positive control, primary antibody, detection system and counterstain were processed as intended before calling another specimen FGF1-negative (HPA: kidney, High; general IHC practice). |
💡Expected FGF1 appearanceA convincing positive is selective cytoplasmic staining in endothelial cells, with high staining reported in kidney glomerular cells; widespread cell-free chromogen or strong staining in HPA-negative cell types warrants review (HPA: tissue IHC profile; kidney, High; adipose tissue and bronchus, Not detected; general IHC practice).
| Tissue and cell-type reference (HPA: tissue IHC). | Kidney glomerular cells are High; adipocytes in adipose tissue and respiratory epithelial cells in bronchus are Not detected. Compare like cell types within the named tissues, since these entries do not classify every cell in either section (HPA: kidney; adipose tissue; bronchus). |
| RNA and protein location (HPA: reliability description). | HPA calls RNA tissue-enriched in brain yet describes selective endothelial cytoplasmic protein staining; it also reports no detection in cerebral-cortex endothelial cells. Because FGF1 can be secreted, RNA location alone is an unreliable slide-level positive-control choice (HPA: RNA specificity; tissue IHC; reliability description). |
| Intracellular and secreted pools (UniProt P05230). | FGF1 lacks a cleavable signal sequence and can move from cytoplasm toward the membrane for non-classical secretion. UniProt also reports nuclear localization. These annotations support checking compartment and morphology together; they do not establish the amount or appearance of extracellular chromogen in a particular paraffin section (UniProt P05230). |
| Antibody validation by application (HPA: antibody validation). | CAB017519 has Enhanced IHC validation, whereas HPA003265 has Supported ICC validation and no IHC status in the supplied record. An ICC localization result therefore cannot establish the expected performance of either antibody in paraffin-section IHC (HPA: antibody validation; subcellular ICC-IF). |
| Processing and isoforms (UniProt P05230). | UniProt lists a propeptide at residues 2–15, a chain at 16–155 and two isoforms. The supplied record gives no antibody epitope, so it cannot predict which molecular forms an IHC stain detects or whether processing changes the observed pattern (UniProt P05230). |
| Antigen retrieval and detection settings (general IHC practice). | Retrieval conditions and detection controls are routine run variables to check when staining fails or background rises. No FGF1-specific retrieval condition, dilution or fixation sensitivity is supplied here; do not infer one from HPA staining levels or UniProt localization (general IHC practice; HPA: tissue IHC; UniProt P05230). |
| Situation | Likely cause | Next action |
|---|---|---|
| Kidney reference section is blank where glomerular cells should stain (HPA: kidney, High). | A failed IHC run or unsuitable control section is possible; absence of chromogen alone does not identify which step failed (general IHC practice). | Repeat with a suitable kidney positive section and inspect primary-antibody, retrieval and detection steps using the antibody's validated IHC instructions (HPA: kidney, High; general IHC practice). |
| Negative-control slide also shows diffuse or cell-free chromogen (general IHC practice). | Background from detection reagents, endogenous activity or nonspecific binding is possible (general IHC practice). | Inspect the negative control alongside the test section; review blocking, washes and detection controls before scoring cell-associated staining (general IHC practice). |
| Unexpected strong staining appears in adipocytes or bronchial respiratory epithelium (HPA: adipose tissue and bronchus, Not detected). | Possible cross-reactivity or endogenous detection activity; the HPA entries support an unexpected-pattern flag, not a unique cause (HPA: tissue IHC; general IHC practice). | Confirm cell identity by morphology, compare control slides and check whether the expected endothelial cytoplasmic pattern is present (HPA: tissue IHC profile; general IHC practice). |
| The section shows nuclear staining but little selective endothelial cytoplasmic staining (HPA: tissue IHC profile). | The tissue IHC pattern differs from HPA's summary, although nuclear FGF1 is biologically plausible and HPA supports nucleoplasmic ICC-IF localization (UniProt P05230; HPA: subcellular ICC-IF). | Check the tissue positive reference, controls and cell morphology; report nuclear staining separately rather than treating it as confirmation of the expected tissue IHC pattern (HPA: tissue IHC; general IHC practice). |
| A brain section is negative despite brain-enriched RNA or UniProt tissue specificity (HPA: RNA specificity; UniProt P05230). | RNA abundance and tissue-wide expression do not guarantee staining in the selected cells; HPA reports cerebral-cortex endothelial cells as Not detected (HPA: reliability description; cerebral cortex). | Use the reported kidney glomerular-cell staining as the IHC reference and describe the exact brain region and cell type examined (HPA: kidney, High; cerebral cortex, Not detected). |
| Why might IF/ICC show nucleoplasmic FGF1 while tissue IHC favors cytoplasmic endothelial staining? (HPA: subcellular ICC-IF; tissue IHC). | HPA's supported nucleoplasmic result comes from ICC-IF, while its selective cytoplasmic profile comes from tissue IHC; UniProt includes both nuclear and cytoplasmic locations (HPA: subcellular ICC-IF; tissue IHC; UniProt P05230). | Interpret each image against its own application and cell context; use the separate IF/ICC guide for that application (HPA: antibody validation; general IHC/IF practice). |
Experiment evidence
IHC & IF images showing FGF1 staining
PB9944 · IHCIHC analysis of GADD45A using anti-GADD45A antibody (PB9944). GADD45A was detected in a paraffin-embedded section of mouse intestine tissue.
PB9944 · IHCIHC analysis of GADD45A using anti-GADD45A antibody (PB9944). GADD45A was detected in a paraffin-embedded section of rat intestine tissue. H
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000113578-FGF1/tissue/cerebral+cortex#imid_4474148
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000113578-FGF1/tissue/colon#imid_4474082
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000113578-FGF1/tissue/liver#imid_4474083
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000113578-FGF1/tissue/kidney#imid_4474068
HPA · ICC-IF U-251MGHuman Protein Atlas immunofluorescence, U-251MG, antibody HPA003265; green = FGF1, blue = nucleus, red = microtubules.
HPA · ICC-IF U-251MGHuman Protein Atlas immunofluorescence, U-251MG, antibody HPA003265; green = FGF1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FGF1 IHC & IF
🧪Run kidney first and expect staining in cells in glomeruli (HPA: High in kidney glomerular cells). Run adipose tissue as a negative comparator because adipocytes are not detected (HPA: Not detected in adipocytes); on the kidney slide, use unstained neighboring cells as background comparators without assuming their FGF1 status (HPA: only glomerular cells are listed as High).
Positive control tissue: Kidney (Cells in glomeruli, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FGF1 in U-251MG, U2OS, with annotated localisation: Nucleoplasm (supported) (HPA subcellular).
Technical controls: Include no-primary (secondary-only), host- and isotype-matched control immunoglobulin, and FGF1 knockout tissue or a validated peptide-block control (standard IHC practice). Check kidney sections for endogenous peroxidase and, if using biotin-based detection, endogenous biotin before interpreting chromogen signal (standard IHC practice).
⚠️Feasibility: A target-specific fixation window and retrieval dependency are unreported in the supplied FGF1 evidence; the selected-SKU paraffin caption describes GADD45A, and its fixative is unreported (selected-SKU caption). The evidence does not establish that frozen sections or IF are easier for FGF1 (supplied target/application evidence). Kidney background from endogenous peroxidase or biotin can complicate chromogenic scoring (standard IHC practice).
HPA tissue IHC evidence for FGF1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. At least one protein variant secreted, tissue location of RNA and protein might differ and correlation is complex.). 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 |
|---|---|---|---|---|
| Kidney | Cells in glomeruli | 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 → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced FGF1 IHC Tips
Use matched controls and cell-level scoring to troubleshoot FGF1 staining in paraffin sections; interpret IF observations separately.
How should I adjust retrieval when FGF1 staining is weak in paraffin sections?
Begin with heat-mediated antigen retrieval in EDTA at pH 8.0 (datasheet PB9944). The cited PB9944 caption documents GADD45A staining in a paraffin section, so this page setting is a starting point rather than FGF1-specific validation (datasheet PB9944). If staining is weak, compare a shorter and a longer heating interval on adjacent sections while keeping the antibody concentration, detection, and development time constant (standard IHC practice). Check tissue preservation and a no-primary control alongside each condition, because stronger colour alone cannot distinguish recovered FGF1 signal from retrieval-related background (standard IHC practice).
Could fixation explain weak or uneven FGF1 staining?
FGF1-specific fixation sensitivity is unknown from the supplied evidence; the cited paraffin-section caption does not report a fixative and concerns GADD45A (datasheet PB9944). Record the fixative, time before fixation, and fixation duration for each block before attributing a staining difference to antigen loss (standard IHC practice). For newly prepared material, a documented 10% neutral buffered formalin pilot can provide a consistent reference condition, but it does not establish an optimal FGF1 fixation time (standard IHC practice). Compare adjacent sections with matched retrieval and detection, and assess tissue morphology before interpreting a weaker result as lower FGF1 abundance (standard IHC practice).
Which FGF1 staining compartments should I expect in tissue?
Assess cellular staining first: HPA describes highly selective cytoplasmic FGF1 expression in endothelial cells and high staining in kidney glomerular cells (HPA tissue IHC). Nuclear staining can also be biologically plausible because FGF1 is annotated in the nucleus and HPA reports supported nucleoplasmic localisation in ICC/IF images (UniProt P05230 localisation; HPA subcellular). FGF1 is secreted through a nonclassical route despite lacking a cleavable signal sequence or transmembrane segment, so extracellular signal requires careful anatomical and control-based review (UniProt P05230 localisation and topology). Record cytoplasmic, nuclear, and extracellular patterns separately rather than merging them into one positive-cell score (standard IHC practice).
How can the antibody epitope affect FGF1 IHC interpretation?
FGF1 has 2 annotated isoforms and a processed chain spanning residues 16–155, with residues 2–15 annotated as a propeptide (UniProt P05230 processing and isoforms). Obtain the catalog antibody's immunogen or epitope information before claiming that its staining covers both isoforms or detects the processed chain (standard IHC practice). If its epitope overlaps a sequence absent from an isoform or removed during processing, staining could vary without a corresponding change in total FGF1 (inference from UniProt P05230 processing and isoforms). Compare epitope information with the annotated sequences and interpret discordant samples using an independently validated reagent or orthogonal measurement (standard IHC practice).
How should I investigate FGF1 localisation by multiplex IF?
On the separate IF/ICC workflow, pair FGF1 with a validated endothelial-cell marker when examining the cell population highlighted by tissue IHC (HPA tissue IHC; standard IF practice). Select spectrally separated fluorophores, favoring a far-red FGF1 channel if tissue autofluorescence overlaps shorter wavelengths, and include single-stain and no-primary controls (standard IF practice). For cytoplasmic or nuclear epitopes, test controlled permeabilisation; for an extracellular epitope, compare a condition without detergent because permeabilisation changes access to intracellular antigen (UniProt P05230 localisation; standard IF practice). HPA supports nucleoplasmic localisation in ICC/IF, but those images do not validate this catalog antibody's IF conditions (HPA subcellular).
What should I check when chromogenic FGF1 staining appears diffuse?
Run a no-primary section through the same secondary antibody, enzyme, and DAB steps to reveal detection-system background (standard chromogenic IHC practice). Block endogenous peroxidase before DAB development and assess whether colour appears in the no-primary section or follows damaged tissue and section edges (standard chromogenic IHC practice). Because FGF1 can be secreted and associated with cell surfaces through its receptor interactions, extracellular colour alone does not establish which cell produced it (UniProt P05230 localisation and function). Recheck blocking, antibody concentration, wash stringency, and development time on adjacent sections, then compare the remaining pattern with HPA's selective endothelial cytoplasmic staining (standard IHC practice; HPA tissue IHC).
How should I score FGF1 staining across tissue samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the anatomical region and cell population before scoring, since HPA reports selective endothelial cytoplasmic staining and high signal in kidney glomerular cells (HPA tissue IHC). For cellular staining, report percent positive cells and an H-score from 0–300, calculated from the percentages at intensity grades 0–3 (standard IHC scoring practice). Normalize cell counts to the number of eligible cells, or report positive-cell density per mm² of the same annotated tissue compartment (standard IHC quantification practice). Score nuclear and cytoplasmic compartments separately, use identical imaging and threshold settings, and review controls before comparing groups (UniProt P05230 localisation; standard IHC practice).
How can I distinguish credible FGF1 staining from artefact?
A credible pattern should be reproducible in matched sections, exceed the no-primary signal, and have a plausible cellular location (standard IHC practice; UniProt P05230 localisation). HPA's selective endothelial cytoplasmic profile and high staining in kidney glomerular cells provide useful comparisons, while its tissue data report adipocytes as not detected (HPA tissue IHC). Do not dismiss every nuclear signal as misplaced: FGF1 has nuclear localisation annotations, and HPA reports supported nucleoplasmic localisation in ICC/IF (UniProt P05230 localisation; HPA subcellular). Treat staining confined to section edges, necrotic areas, or endogenous-enzyme-positive controls as suspect, and confirm any unexpected cell population with independent evidence (standard IHC practice).
Boster reagents
Best FGF1 / Fibroblast growth factor 1 IHC Antibodies
The catalog lists anti-FGF1 antibodies for human, mouse and rat IHC (catalog: applications/reactivity). Its only IHC images are labeled GADD45A, leaving FGF1 staining unverified (PB9944 image captions).
Real IHC data
Anti-FGF1 Antibody ®
Cat # PB9944
M00206-1 is listed for human, mouse and rat IHC, and RP1005 for human IHC; neither has an IHC image (catalog: applications/reactivity/image alts). PB9944 is listed for human, mouse and rat IHC, but its paraffin-section images are labeled GADD45A in mouse and rat intestine and human placenta (PB9944 image captions).
Which to pick: For cross-species tissue IHC, M00206-1 is a rabbit monoclonal listed for human, mouse and rat, though it has no IHC image (catalog: host/clone/applications/reactivity/image alts). RP1005 is listed for human IHC; PB9944's caption shows paraffin sections but names GADD45A and does not report the fixative, so it cannot establish FGF1 staining or fixation (catalog: RP1005 applications/reactivity; PB9944 image captions). None of these SKUs lists IF/ICC, so there is no supported IF/ICC pick here (catalog: applications). The selected PB9944 tissue-IHC caption documents paraffin sections, but does not specify the fixative (selected-SKU IHC image PB9944).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P05230 (FGF1_HUMAN, Fibroblast growth factor 1).
- Human Protein Atlas. FGF1 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. FGF1 subcellular location (ICC-IF): Localized to the nucleoplasm..
- Human Protein Atlas. FGF1 antibody validation summary (2 antibodies).
- Comparison of FGF1 (aFGF) expression between the dorsal motor nucleus of vagus and the hypoglossal nucleus of rat. Acta histochemica et cytochemica 2006 — PMC1831852.
- Increased FGF1-FGFRc expression in idiopathic pulmonary fibrosis. Respiratory research 2015 — PMC4495640.
- Expression and clinical significance of fibroblast growth factor 1 in gastric adenocarcinoma. OncoTargets and therapy 2015 — PMC4360790.
- Characterization of FN1-FGFR1 and novel FN1-FGF1 fusion genes in a large series of phosphaturic mesenchymal tumors. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2016 — PMC13417894.
- PubMed PMID:3523756 — UniProt-cited evidence.
- PubMed PMID:2590193 — UniProt-cited evidence.
- PubMed PMID:2474753 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FGF1 (Fibroblast growth factor 1). Expected localisation Endothelial cytoplasm (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet PB9944). Validated IHC antibody: PB9944 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Kidney (Cells in glomeruli); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded mouse intestine tissue; fixative not specified (datasheet PB9944); 2. Fixation: Image fixative and duration unreported (datasheet PB9944); 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 PB9944); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet PB9944); 8. Primary antibody: Rabbit anti-FGF1, 0.5-1μg/ml (datasheet PB9944); 9. Primary incubation: Overnight at 4 °C (datasheet PB9944). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Secretion may separate FGF1 staining from its source cells (UniProt); Isoform / epitope: 2 isoforms; antibody epitope coverage is unknown (UniProt); Regulation: Expression regulation not established (UniProt). Evidence: UniProt P05230, HPA tissue IHC · Enhanced, HPA ICC-IF · nucleoplasm., Datasheet PB9944, PMC1831852, PMC4360790. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FGF1/immunohistochemistry-ihc-guide.