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FBN1 / Fibrillin-1 · IHC design guide
Design Immunohistochemistry for FBN1
FBN1 is an extracellular matrix protein with membranous and cytoplasmic tissue IHC staining in stromal and smooth muscle cells (UniProt; HPA tissue IHC). This guide covers fixation, chromogenic staining and interpretation using adipose tissue and endometrial stroma as positive references (standard IHC practice; HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FBN1 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 | Extracellular matrix with membranous/cytoplasmic signal (HPA tissue IHC) | |
| Staining pattern | Membranous/cytoplasmic in stroma, smooth muscle and decidua (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Adipose tissue+4 more · see all | |
| Negative control | Adrenal gland+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 | Secreted FBN1 may stain away from its RNA source (HPA tissue IHC) | |
| Regulation | Tissue-enhanced RNA: adipose, placenta (HPA tissue RNA) | |
| Isoform / epitope | No isoforms; cleavage separates fibrillin-1 and asprosin epitopes (UniProt) |
Section 1
Recommended FBN1 IHC & IF Protocols
The catalog antibody protocol is paired with two published FBN1 IHC protocols for ovarian cancer and rat synovial tissue (PMC8923131; PMC13276305).
| Sample | Paraffin-embedded human breast carcinoma tissue; fixative not specified (datasheet A00559) |
| Fixation | Image fixative and duration unreported (datasheet A00559); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane 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-FBN1, 1:50-1:200 (datasheet A00559) |
| 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 | FBN1-positive staining in adipocytes of adipose tissue (HPA tissue IHC: High). HPA tissue profile: Membranous and cytoplasmic expression in extracellular matrix, stromal cells, smooth muscle cells and decidual cells. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page retrieval setting); assess extracellular matrix staining (UniProt P35555 localization).
Section 2
What Is the Expected FBN1 Staining Pattern?
FBN1 is a secreted, extracellular matrix microfibril protein with no transmembrane segment (UniProt P35555 topology and function). In tissue IHC, look for staining in extracellular matrix and around stromal, smooth muscle, and decidual cells; HPA also describes membranous and cytoplasmic staining in these settings (HPA: tissue IHC profile). HPA rates the tissue pattern Enhanced and cautions that RNA and protein locations can differ for secreted proteins (HPA: reliability description).
| Extracellular or cell-associated staining in stroma, with signal in decidual or smooth muscle cells. | This fits the reported tissue pattern (HPA: tissue IHC profile). Read adjacent matrix and cells together: secreted FBN1 may be found away from the cell that produced it (UniProt P35555 subcellular location; HPA: reliability description). |
| Strong, predominantly nuclear staining with little extracellular or stromal signal. | A nuclear-dominant pattern is outside the reported tissue profile and is a reason to question specificity or detection artefact (HPA: tissue IHC profile; general IHC practice). Do not score it as convincing FBN1 solely because nuclei are sharply stained. |
| Signal confined to a cell population reported as undetected in that tissue. | For example, HPA reports no staining in bronchial respiratory epithelial cells or bone-marrow hematopoietic cells (HPA: tissue IHC negatives). Check for cross-reactivity or endogenous detection activity before interpreting that signal as FBN1 (general IHC practice); an undetected cell population does not make its entire tissue a negative control. |
| Diffuse chromogen across the section, including areas without discernible structures. | Diffuse background obscures the expected matrix and cell-associated distribution (HPA: tissue IHC profile). Compare with a no-primary control and inspect blocking, washing, and detection steps before assigning intensity scores (general IHC practice). |
| No signal in a tissue and cell population reported as strongly stained. | Adipose-tissue adipocytes, endometrial stromal cells, and placental decidual cells are reported High (HPA: tissue IHC positives). First verify that the relevant cells are present; then review antibody and detection performance with a positive control (general IHC practice). The absence alone does not identify the failed step. |
💡Expected FBN1 appearanceCall a section positive when discernible extracellular or cell-associated stromal staining accompanies the expected cell pattern, potentially strong in HPA High populations; isolated nuclear staining or uniform background is unconvincing (HPA: tissue IHC profile and positives; general IHC practice).
| Tissue and cell context | HPA reports High staining in adipose-tissue adipocytes, endometrial stromal cells, and placental decidual cells, but no detection in breast adipocytes (HPA: tissue IHC positives and negatives). Select and score controls by the specified tissue and cell population, not by cell name alone. |
| Secretion and matrix assembly | FBN1 is secreted and forms extracellular matrix microfibrils (UniProt P35555 subcellular location and function). Its tissue protein distribution need not match the cells with the most RNA; HPA explicitly cautions about this for secreted proteins (HPA: reliability description). |
| Maturation and epitope position | The precursor has a signal peptide, propeptide, Fibrillin-1 chain, and Asprosin chain, with separation after secretion (UniProt P35555 processing and subcellular location). Interpret a stain against the antibody's documented epitope if available; the supplied antibody entries provide no epitope position. |
| Antibody evidence | Five listed antibodies have Enhanced IHC validation, while CAB080202 is Supported (HPA: antibody validation). This supports the reported tissue pattern but does not establish that every listed antibody has identical epitope recognition, background, or performance in a particular section. |
| IF/ICC Q&A | What should an IF/ICC image show? HPA reports mainly Golgi localization and an additional, uncertain plasma-membrane localization in its cell images (HPA: subcellular ICC-IF). That cell-image observation is distinct from the tissue IHC profile and should not be used as an IHC compartment requirement (HPA: tissue IHC profile). |
| Fixation and retrieval evidence | Target-specific fixation sensitivity and retrieval conditions are unreported in the supplied UniProt and HPA records. Any retrieval adjustment is a general IHC workflow decision, not an established FBN1 effect (general IHC practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| A reported High population stains weakly or not at all. | The expected cells may be absent from the section, or the staining workflow may have failed; the image alone cannot distinguish these possibilities (HPA: tissue IHC positives; general IHC practice). | Confirm the cells on the counterstained section and run a reported High tissue alongside the sample; then check antibody, detection reagents, and controls (HPA: tissue IHC positives; general IHC practice). |
| Only nuclei stain prominently. | The compartment does not match the extracellular, membranous, and cytoplasmic tissue profile (HPA: tissue IHC profile). | Compare a no-primary control and another IHC-validated antibody where available; withhold an FBN1-positive call until the expected distribution is visible (HPA: antibody validation; general IHC practice). |
| A reported undetected cell population stains. | Cross-reactivity or endogenous detection activity is possible; HPA's negative calls apply to named populations within specified tissues (HPA: tissue IHC negatives; general IHC practice). | Identify the stained cells, compare the matching HPA tissue entry, and inspect no-primary and detection controls before interpreting the signal (HPA: tissue IHC negatives; general IHC practice). |
| Background makes matrix boundaries hard to see. | Non-specific antibody binding or detection background may obscure the reported extracellular distribution (HPA: tissue IHC profile; general IHC practice). | Use a no-primary control, then review blocking, washes, and detection conditions; score only structures distinguishable from background (general IHC practice). |
| Cell staining is visible but nearby matrix appears unstained. | HPA reports both cell-associated and extracellular staining; one compartment alone gives an incomplete view of the reported pattern (HPA: tissue IHC profile). | Inspect adjacent stroma and a reported positive control at the same magnification and detection settings before drawing a localization conclusion (HPA: tissue IHC positives; general IHC practice). |
| Tissue IHC looks extracellular, while an IF/ICC image looks intracellular. | HPA's tissue profile includes extracellular matrix, whereas its ICC-IF summary names the Golgi as the main location (HPA: tissue IHC profile; HPA: subcellular ICC-IF). | Interpret each image in its own sample context; use the tissue IHC profile to score paraffin sections and the ICC-IF entry to interpret cell images (HPA: tissue IHC profile and subcellular ICC-IF). |
Experiment evidence
IHC & IF images showing FBN1 staining
A00559 · IHCImmunohistochemistry (IHC) analyzes of FBN1 (N2843) pAb in paraffin-embedded human breast carcinoma tissue at 1:100.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000166147-FBN1/tissue/cerebral+cortex#imid_19245269
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000166147-FBN1/tissue/colon#imid_19245195
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000166147-FBN1/tissue/liver#imid_19245204
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000166147-FBN1/tissue/kidney#imid_19245213
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA017759; green = FBN1, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA017759; green = FBN1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FBN1 IHC & IF
🧪Run endometrium first and expect staining in the stroma around endometrial stromal cells (HPA: High in cells in endometrial stroma). Run bone marrow as the negative tissue, focusing on hematopoietic cells (HPA: Not detected in hematopoietic cells); on the endometrium slide, use cells without specific staining as internal background comparators and score nearby extracellular matrix separately (UniProt P35555: extracellular matrix localization).
Positive control tissue: Adipose tissue (Adipocytes, HPA High)
Negative control tissue: Adrenal gland (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FBN1 in A-431, U-251MG, U2OS, with annotated localisation: Golgi apparatus (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control; an isotype control matched to the primary antibody’s host species, immunoglobulin class, and concentration; and FBN1-knockout material where available or an immunizing-peptide block when the peptide is known (standard IHC practice). For chromogenic HRP detection, quench endogenous peroxidase and check stromal background; block endogenous biotin if using biotin-based detection (standard IHC practice).
⚠️Feasibility: No target-specific fixation window or antigen-retrieval dependency is reported in the supplied evidence; the A00559 paraffin-section caption does not report a fixative (caption: human breast carcinoma tissue at 1:100). Paraffin-section IHC is documented by that caption, but the evidence does not establish whether frozen sections or IF are easier. In endometrium, extracellular microfibrils can make stromal matrix signal appear cell-associated, so score matrix and cells separately (UniProt P35555: extracellular microfibrils; HPA: High in cells in endometrial stroma).
HPA tissue IHC evidence for FBN1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — High consistency between antibody staining and RNA expression data. Secreted protein, tissue location of RNA and protein is expected to differ. 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 |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | High | Protein (IHC) | HPA → |
| Endometrium | Cells in endometrial stroma | High | Protein (IHC) | HPA → |
| Placenta | Decidual cells | High | Protein (IHC) | HPA → |
| Ovary | Ovarian stroma cells | Medium | Protein (IHC) | HPA → |
| Smooth muscle | Smooth muscle cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| 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 → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced FBN1 IHC Tips
Troubleshoot FBN1 staining by checking retrieval, matrix localisation, epitope coverage and the distinction between deposited fibrils and cellular signal.
How should I retrieve FBN1 in paraffin sections when staining is weak?
Start with citrate buffer at pH 6.0, heated to 95–98 °C for 20 min (page-specified retrieval). If matrix staining remains weak, compare a shorter or longer heating time on matched sections while holding antibody dilution and detection constant; excessive retrieval can damage morphology and increase background (standard IHC practice). The selected antibody has a paraffin-section image at 1:100, but its caption does not report a retrieval method (A00559 tissue-IHC caption). Evaluate improvement in extracellular fibrillar signal, since FBN1 is a structural component of matrix microfibrils (UniProt P35555 function and localisation).
Could fixation explain weak or uneven FBN1 staining in my sections?
Target-specific fixation sensitivity is unknown because the supplied FBN1 tissue-IHC caption gives no fixative or fixation duration (A00559 tissue-IHC caption). Record the fixative and processing history for each specimen, then compare matched sections processed alike before changing antibody concentration or retrieval (standard IHC practice). Underfixation, prolonged fixation and uneven reagent penetration can each complicate staining or morphology, but none is established here as a specific FBN1 effect (standard IHC practice). Use the page’s citrate pH 6.0, 95–98 °C, 20 min retrieval as a controlled starting point, and judge staining against preserved tissue structure (page-specified retrieval; standard IHC practice).
Where should a convincing FBN1 IHC signal appear?
Prioritise extracellular, fibrillar or pericellular matrix staining because mature Fibrillin-1 contributes to extracellular microfibrils (UniProt P35555 localisation and function). HPA also describes membranous and cytoplasmic staining in extracellular matrix, stromal cells, smooth muscle cells and decidual cells, so record those compartments separately (HPA tissue IHC profile). A cellular signal alone needs cautious interpretation: FBN1 is secreted, and its precursor is processed during secretion (UniProt P35555 localisation and processing). Check whether the same pattern persists across intact tissue regions and disappears in a no-primary control before assigning a diffuse cytoplasmic or nuclear deposit to FBN1 (standard IHC practice; UniProt P35555 localisation).
How can epitope placement change what this FBN1 stain means?
Determine the antibody’s mapped epitope before interpreting a loss of staining, because no epitope coordinates are supplied for the selected antibody (A00559 tissue-IHC caption). The precursor has a signal peptide at residues 1–24, a Fibrillin-1 chain at 45–2731 and an Asprosin chain at 2732–2871; the chains separate after secretion (UniProt P35555 processing and localisation). An antibody against the Asprosin region cannot be assumed to report deposited Fibrillin-1 microfibrils (UniProt P35555 processing and function). The record lists 0 isoforms and extensive glycosylation, but supplies no evidence that either causes this antibody’s particular staining pattern (UniProt P35555 isoforms and glycosylation; A00559 tissue-IHC caption).
How should I investigate a discordant FBN1 IF pattern?
For multiplex IF, pair FBN1 with a validated marker of the cell population being examined, then assess whether FBN1 outlines its surrounding matrix or overlaps cellular staining (UniProt P35555 localisation; HPA tissue IHC profile; standard IF practice). Choose fluorophores after checking the specimen’s autofluorescence in unstained controls, and reserve a spectrally distinct channel for weak FBN1 signal (standard IF practice). Extracellular epitopes may be accessible without detergent, whereas investigating intracellular Golgi signal generally requires permeabilisation after fixation; the antibody’s epitope location is unreported (UniProt P35555 localisation; HPA subcellular profile; A00559 tissue-IHC caption; standard IF practice). Optimise IF separately because the supplied 1:100 image documents paraffin-section IHC, not an IF dilution (A00559 tissue-IHC caption).
What should I change when FBN1 IHC has diffuse brown background?
First inspect a no-primary control and compare background in matrix-rich and cell-rich regions; this helps separate detection-system signal from antibody-dependent staining (standard IHC practice). Verify the peroxidase block when using horseradish peroxidase and DAB, and check that blocking, washes and antibody titration are adequate (standard chromogenic IHC practice). Use 1:100 only as the reported concentration for the selected paraffin-section image, not as an established optimum for every specimen (A00559 tissue-IHC caption). A believable FBN1 pattern should retain spatial structure consistent with extracellular microfibrils rather than uniform stain across unrelated compartments (UniProt P35555 function and localisation; standard IHC interpretation).
How should I quantify FBN1 when matrix and cells both stain? ⚠ ANSWER MARKED FOR VERIFICATION
Define matrix and cellular regions before scoring, because FBN1 is an extracellular microfibril component while HPA also reports cellular staining (UniProt P35555 function and localisation; HPA tissue IHC profile). For the matrix, measure positive fibrillar area or length per mm² of evaluable matrix, excluding folds, necrosis and section edges (standard image-analysis practice). If cellular staining is biologically relevant, report the percentage of positive cells and an H-score separately, with the cell population and threshold stated (standard IHC scoring practice). Normalise each comparison to the same compartment area or eligible cell count, and keep retrieval, detection and imaging settings consistent across samples (standard IHC quantification practice).
How can I distinguish true FBN1 staining from artefact?
Look for reproducible extracellular or pericellular fibrillar staining within preserved tissue, consistent with FBN1’s role in matrix microfibrils (UniProt P35555 function and localisation; standard IHC interpretation). HPA reports staining in stromal and smooth muscle cells and decidual cells, so annotate those signals without assuming every brown cell marks deposited fibrillin (HPA tissue IHC profile; UniProt P35555 localisation). Treat isolated nuclear staining, sharp edge-only signal and staining over necrosis as suspect until controls and adjacent intact regions support them (UniProt P35555 localisation; standard IHC interpretation). A no-primary control helps identify endogenous enzyme or detection background, while matched positive tissue and consistent processing help assess a suspected false negative (standard chromogenic IHC practice).
Boster reagents
Best FBN1 / Fibrillin-1 IHC Antibodies
An IHC image documents FBN1 staining in paraffin-embedded human breast carcinoma with A00559; the catalog lists human, mouse and rat reactivity (A00559 image caption; catalog: reactivity). No IF image is supplied (catalog: image captions).
Real IHC data
Anti-FBN1 (N2843) Antibody
Cat # A00559
The rendered card is A00559, listed for human, mouse and rat IHC, with a paraffin-embedded human breast carcinoma image at 1:100 (catalog: applications and reactivity; A00559 image caption). A00559-1 is listed for human IHC and IF/ICC, but has no supplied IHC or IF image and will not render as a card (catalog: applications, reactivity and image captions; card list).
Which to pick: For paraffin-section IHC, choose A00559: its own image documents that preparation at 1:100, while the fixative is unreported (A00559 image caption). For IF/ICC, A00559-1 lists those applications in human samples, though no image is supplied (catalog: A00559-1 applications, reactivity and image captions). For mouse or rat IHC, A00559 lists reactivity with both species; its supplied image documents human tissue only (catalog: A00559 reactivity; A00559 image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P35555 (FBN1_HUMAN, Fibrillin-1).
- Human Protein Atlas. FBN1 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. FBN1 subcellular location (ICC-IF): Mainly localized to the Golgi apparatus. In addition localized to the plasma membrane..
- Human Protein Atlas. FBN1 antibody validation summary (6 antibodies).
- The Fibrillin-1/VEGFR2/STAT2 signaling axis promotes chemoresistance via modulating glycolysis and angiogenesis in ovarian cancer organoids and cells. Cancer communications (London, England) 2022 — PMC8923131.
- MFAP5(+) synovial fibroblasts drive LOX upregulation to promote osteoarthritis progression. iScience 2026 — PMC13276305.
- Fibrillin-1-enriched microenvironment drives endothelial injury and vascular rarefaction in chronic kidney disease. Science advances 2021 — PMC7840119.
- Deciphering the immune landscape dominated by cancer-associated fibroblasts to investigate their potential in indicating prognosis and guiding therapeutic regimens in high grade serous ovarian carcinoma. Frontiers in immunology 2022 — PMC9478207.
- PubMed PMID:8364578 — UniProt-cited evidence.
- PubMed PMID:15221638 — UniProt-cited evidence.
- PubMed PMID:16572171 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FBN1 (Fibrillin-1). Expected localisation Extracellular matrix with membranous/cytoplasmic signal (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A00559 at 1:50-1:200 (the product's own IHC validation image is shown). Controls (HPA): positive Adipose tissue (Adipocytes); negative Adrenal gland. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human breast carcinoma tissue; fixative not specified (datasheet A00559); 2. Fixation: Image fixative and duration unreported (datasheet A00559); 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-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 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-FBN1, 1:50-1:200 (datasheet A00559); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Secreted FBN1 may stain away from its RNA source (HPA tissue IHC); Isoform / epitope: No isoforms; cleavage separates fibrillin-1 and asprosin epitopes (UniProt); Regulation: Tissue-enhanced RNA: adipose, placenta (HPA tissue RNA). Evidence: UniProt P35555, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the Golgi apparatus. In addition localized to…, Datasheet A00559, PMC8923131, PMC13276305. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FBN1/immunohistochemistry-ihc-guide.