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SMAD1 / SMAD family member 1 · IHC design guide
Design Immunohistochemistry for SMAD1
Plan SMAD1 IHC in paraffin sections using cytoplasmic and nuclear staining as the tissue reference (HPA tissue IHC). Epididymal and stomach glandular cells stain strongly, while adrenal glandular cells are not detected; interpret results in light of the reported low consistency between staining and RNA expression (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
SMAD1 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 staining (HPA tissue IHC) | |
| Staining pattern | Most tissues show cytoplasmic and nuclear staining (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6 HIER, heat-mediated (datasheet M00728-3) | |
| Positive control | Epididymis+4 more · see all | |
| Negative control | Adrenal gland+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Formaldehyde-fixed paraffin sections were used (selected-SKU IHC image M00728-3) | |
| Caveat | Staining has low consistency with RNA expression (HPA tissue IHC) | |
| Regulation | BMP signaling drives nuclear translocation (UniProt) | |
| Isoform / epitope | 2 isoforms; epitope coverage is unspecified (UniProt) |
Section 1
Recommended SMAD1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol uses citrate pH 6 retrieval (datasheet: M00728-3). The published options cover Smad1 in children’s surgical samples and p-Smad1/5/8 in mouse femur (PMC6566125; PMC12316925).
| Sample | Formaldehyde-fixed, paraffin-embedded human skeletal muscle tissue (datasheet M00728-3) |
| Fixation | Image formalin-fixed; duration unreported (datasheet M00728-3); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: Citrate pH 6 (datasheet M00728-3); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Mouse monoclonal (clone 1356CT119.18.55) anti-SMAD1, 1:25 (datasheet M00728-3) |
| Primary incubation | 1 hours at 37°C (datasheet M00728-3) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | SMAD1-positive staining in glandular cells of epididymis (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic and nuclear expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6 heat retrieval for the catalog antibody (datasheet: M00728-3). The mouse femur protocol measures p-Smad1/5/8, so interpret it as phospho-group staining (PMC12316925).
Section 2
What Is the Expected SMAD1 Staining Pattern?
SMAD1 is a non-membrane protein found in cytoplasm and nucleus (UniProt Q15797 topology and subcellular location). In paraffin-section IHC, expect staining in glandular cells of epididymis and stomach, with weaker or absent staining in some other cell types (HPA tissue IHC). HPA describes cytoplasmic and nuclear expression in most tissues, but rates its IHC evidence Approved with low consistency between antibody staining and RNA expression data (HPA tissue IHC).
| Glandular cells in epididymis or stomach show clear cytoplasmic staining, with nuclear staining in some cells (HPA tissue IHC). | This fits HPA's High staining in those cell types and its cytoplasmic and nuclear tissue profile (HPA tissue IHC). Score the two compartments separately: UniProt describes cytoplasmic SMAD1 without ligand and nuclear migration when complexed with SMAD4 (UniProt Q15797 subcellular location). Nuclear staining alone does not establish pathway activation. |
| The dominant signal outlines cell membranes or extracellular material, with little cytoplasmic or nuclear staining. | That distribution conflicts with the reported cytoplasm and nucleus locations and absence of a transmembrane segment (UniProt Q15797 topology and subcellular location). Treat it as suspect staining and compare it with a known-positive tissue and a detection-control section before scoring cells as SMAD1-positive (general IHC practice). |
| Strong signal appears in adrenal gland glandular cells or esophageal squamous cells. | HPA reports SMAD1 as not detected in those specific cell populations (HPA tissue IHC). Unexpected staining can reflect cross-reactivity or endogenous detection activity; the pattern alone cannot distinguish them (general IHC practice). Check the cell identity and compare with positive and detection controls. |
| Chromogen forms a diffuse haze across cells, stroma and otherwise empty areas. | A broad haze is difficult to reconcile with a cell-associated cytoplasmic or nuclear pattern (HPA tissue IHC; UniProt Q15797 subcellular location). It may obscure genuine staining. Review blocking, washes and chromogen development, and inspect a section processed without primary antibody (general IHC practice). |
| Epididymal or stomach glandular cells show no discernible signal. | An absent result in these HPA High cell populations calls the run's sensitivity into question (HPA tissue IHC). Confirm that the intended cells are present and review the IHC-validated antibody's stated IHC-P conditions, detection reagents and controls (general IHC practice). HPA's low staining–RNA consistency limits certainty for an individual specimen (HPA tissue IHC). |
💡Expected SMAD1 appearanceCall a result positive when glandular cells in epididymis or stomach show convincing High cell-associated cytoplasmic staining, with possible nuclear staining (HPA tissue IHC; UniProt Q15797 subcellular location); membrane outlines or acellular haze are suspect patterns (UniProt Q15797 topology; general IHC practice).
| Tissue and cell selection | HPA records High glandular-cell staining in epididymis and stomach, Medium in appendix and breast glandular cells, and Low in endometrial glandular cells (HPA tissue IHC). Select and score the named cell population rather than assigning one intensity to an entire section. |
| Biological compartment | SMAD1 can be cytoplasmic or nuclear; ligand-associated SMAD4 complex formation accompanies nuclear migration, and dephosphorylation accompanies nuclear export (UniProt Q15797 subcellular location and function). Record nuclear and cytoplasmic staining independently; localization is suggestive, not a standalone measure of BMP signaling. |
| Validation limit | The listed rabbit polyclonal antibody CAB005389 has IHC status Approved (HPA antibodies). HPA also reports low consistency between antibody staining and RNA expression (HPA tissue IHC). Use the tissue pattern as a guide, then interpret unexpected cell populations cautiously. |
| Isoforms and modifications | UniProt lists 2 SMAD1 isoforms and phosphorylation sites including Ser463 and Ser465 (UniProt Q15797 isoforms and modified residues). The supplied evidence does not identify the IHC antibody's epitope or show how these differences affect its staining; do not infer phospho-SMAD1 from total-SMAD1 staining. |
| IF/ICC: where should signal appear? | HPA reports supported nucleoplasm and cytosol localization, with ICC-IF images from MCF-7 and U2OS (HPA subcellular). This answers the localization question for IF/ICC; it does not establish an IHC-P protocol or an IF staining intensity for other cells. |
| Situation | Likely cause | Next action |
|---|---|---|
| No staining in the intended positive cells. | The sampled cells may be absent, or the IHC run may have insufficient detection sensitivity; HPA reports High glandular-cell staining in epididymis and stomach (HPA tissue IHC). | Verify cell identity on the section, review the IHC-validated antibody's stated IHC-P conditions, and confirm detection reagents with a positive control (general IHC practice). |
| Only membrane-edge staining appears. | Membrane-restricted staining does not match SMAD1's cytoplasm and nucleus locations or its lack of a transmembrane segment (UniProt Q15797 topology and subcellular location). | Check whether true intracellular staining is present in a positive control; examine the no-primary control for edge staining (general IHC practice). |
| Strong staining occurs in an HPA-negative cell population. | HPA reports adrenal gland glandular cells and esophageal squamous cells as not detected (HPA tissue IHC); nonspecific binding or endogenous detection activity is possible (general IHC practice). | Confirm the stained cell type, inspect a no-primary control, and review detection blocking before interpreting the signal as SMAD1 (general IHC practice). |
| Diffuse chromogen masks cell boundaries. | Excess background can obscure the reported cytoplasmic and nuclear distribution (HPA tissue IHC; general IHC practice). | Compare the no-primary control, then review blocking, wash steps and chromogen development time (general IHC practice). |
| Nuclear staining varies between neighboring cells. | SMAD1 moves between cytoplasm and nucleus in its signaling cycle (UniProt Q15797 subcellular location and function); variation alone does not prove a technical failure or pathway activation. | Score nuclear and cytoplasmic compartments separately and compare cells of the same type under the same staining conditions (general IHC practice). |
| The result conflicts with expected RNA abundance. | HPA explicitly reports low consistency between SMAD1 antibody staining and RNA expression despite an Approved IHC reliability rating (HPA tissue IHC). | Recheck tissue and cell identification and the control sections; report the observed IHC pattern without treating RNA abundance as proof of the protein pattern (HPA tissue IHC; general IHC practice). |
Experiment evidence
IHC & IF images showing SMAD1 staining
M00728-3 · IHCM00728-3 staining SMAD1 in human skeletal muscle tissue sections by Immunohistochemistry (IHC-P -paraformaldehyde-fixed, paraffin-embedded s
M00728-3 · IHCM00728-3 staining SMAD1 in human colon tissue sections by Immunohistochemistry (IHC-P -paraformaldehyde-fixed, paraffin-embedded sections).
M00728-3 · IFImmunofluorescent analysis of 4% paraformaldehyde-fixed, 0.1% Triton X-100 permeabilized HeLa (human cervical epithelial adenocarcinoma cell
M00728 · IHCImmunohistochemical analysis of paraffin-embedded human colon, using Smad1 Antibody.
M00728-1 · IHCImmunohistochemical analysis of paraffin-embedded human kidney, using Smad1 Antibody.
M00728-1 · IFImmunofluorescent analysis using the Antibody at 1:50 dilution.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000170365-SMAD1/tissue/cerebral+cortex#imid_2162352
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000170365-SMAD1/tissue/colon#imid_2162294
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000170365-SMAD1/tissue/liver#imid_2162279
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000170365-SMAD1/tissue/kidney#imid_2162288
HPA · ICC-IF MCF-7Human Protein Atlas immunofluorescence, MCF-7, antibody CAB005389; green = SMAD1, blue = nucleus, red = microtubules.
HPA · ICC-IF MCF-7Human Protein Atlas immunofluorescence, MCF-7, antibody CAB005389; green = SMAD1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for SMAD1 IHC & IF
🧪Run epididymis first and require staining in its glandular cells (HPA: High in epididymis glandular cells). Use adrenal gland glandular cells as the negative tissue (HPA: Not detected); on the positive slide, treat nonglandular cells as internal negatives only where they lack specific staining.
Positive control tissue: Epididymis (Glandular cells, HPA High)
Negative control tissue: Adrenal gland (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show SMAD1 in MCF-7, U2OS, with annotated localisation: Nucleoplasm (supported), Cytosol (supported) (HPA subcellular).
Technical controls: Include no-primary (secondary-only) and host-species-, clonality-, and concentration-matched isotype controls, plus a SMAD1-knockout sample as a biological negative (standard IHC controls). For chromogenic epididymis sections, block endogenous peroxidase and check for endogenous biotin if using biotinylated detection (selected-SKU caption: biotinylated secondary antibody).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the exact selected-SKU tissue-IHC caption leaves the fixative unreported (selected-SKU caption: fixative unreported). The caption uses heat-mediated citrate retrieval at pH 6, but does not establish that retrieval is required (selected-SKU caption: citrate buffer pH 6). Frozen-section feasibility and whether IF is easier are unreported; ICC-IF images exist for MCF-7 and U2OS (HPA subcellular: ICC-IF images), and no epididymis-specific artefact is reported in the supplied evidence.
HPA tissue IHC evidence for SMAD1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low 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 |
|---|---|---|---|---|
| Epididymis | Glandular cells | High | Protein (IHC) | HPA → |
| Stomach | Glandular cells | High | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Medium | Protein (IHC) | HPA → |
| Breast | Glandular cells | Medium | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial 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 → |
| Esophagus | Squamous epithelial cells | Not detected | Protein (IHC) | HPA → |
| Liver | Cholangiocytes | Not detected | Protein (IHC) | HPA → |
| Ovary | Ovarian stroma cells | Not detected | Protein (IHC) | HPA → |
| Parathyroid gland | Glandular cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced SMAD1 IHC Tips
Use compartment aware controls and consistent section processing to troubleshoot SMAD1 staining in chromogenic IHC of paraffin sections.
What retrieval should I try first when SMAD1 staining is weak?
Start with heat mediated retrieval in citrate buffer at pH 6 (datasheet M00728-3). The selected tissue IHC example used that retrieval before primary antibody incubation at 1:25 for 1 hour at 37°C (caption M00728-3). If staining remains weak, vary heating duration while keeping section thickness, detection chemistry and the comparison tissue constant (standard IHC practice). Compare nuclear and cytoplasmic signal in the same cell population, because SMAD1 can occupy both compartments (UniProt Q15797; HPA tissue IHC). Excessive retrieval can damage morphology and complicate compartment scoring, so inspect the counterstain alongside signal (standard IHC practice).
How should I troubleshoot variable SMAD1 staining after fixation?
Target specific sensitivity of SMAD1 staining to fixation is unknown from the supplied evidence (supplied fixation evidence). Record fixative, fixation duration, section age and processing history for every specimen, then compare sections processed together (standard IHC practice). When a weak case differs from a strong one, repeat staining with matched retrieval and detection settings before attributing the difference to SMAD1 abundance (standard IHC practice). Check nuclear detail and cytoplasmic preservation on the counterstain, since poor morphology makes compartment assignment unreliable (standard IHC practice). A fixation comparison needs matched tissue and controlled processing; the reported tissue staining pattern alone cannot establish fixation sensitivity (standard IHC practice).
Should SMAD1 staining appear in nuclei, cytoplasm, or both?
Score nuclear and cytoplasmic staining separately: SMAD1 is cytoplasmic without ligand and can enter the nucleus in a complex with SMAD4 (UniProt Q15797). Tissue IHC reports cytoplasmic and nuclear expression in most tissues, while cell imaging supports nucleoplasm and cytosol localisation (HPA tissue IHC; HPA subcellular). Compare cells within the same anatomical compartment and use a nuclear counterstain to confirm that apparent nuclear signal lies inside intact nuclei (standard IHC practice). A shift toward nuclear staining may fit BMP pathway activation, but total SMAD1 IHC alone does not establish receptor phosphorylation or transcriptional activity (UniProt Q15797; standard IHC interpretation).
Can this stain distinguish SMAD1 isoforms or phosphorylation states?
SMAD1 has 2 listed isoforms, and its MH1 and MH2 domains span residues 12–136 and 271–465, respectively (UniProt Q15797). The supplied IHC evidence does not identify this antibody's binding epitope or demonstrate isoform discrimination (supplied antibody evidence). Unless an epitope map and cross reactivity data establish specificity, report the result as SMAD1 immunoreactivity rather than an individual isoform (standard IHC interpretation). Phosphorylation is recorded at residues 322, 463 and 465, but a total protein stain cannot identify those modifications without modification specific validation (UniProt Q15797; standard IHC interpretation).
How can I adapt SMAD1 localisation checks to multiplex IF?
For a separate IF experiment, pair SMAD1 with a marker of the expected cell population, such as a glandular epithelial marker when examining the reported glandular staining pattern (HPA tissue IHC; standard IF practice). Select spectrally separated fluorophores after checking tissue autofluorescence, and place the weaker signal in the cleaner channel (standard IF practice). SMAD1 has no transmembrane segment and is reported in cytosol and nucleoplasm, so permeabilise sufficiently for intracellular access while preserving nuclear morphology (UniProt Q15797; HPA subcellular; standard IF practice). Include single stain and secondary only controls to assess bleed through and background before comparing compartments (standard IF practice).
What should I check when SMAD1 staining is diffuse or granular?
Run a section without primary antibody to identify signal from the detection system, and inspect unstained tissue for pigment that could resemble chromogen (standard IHC practice). The selected example used 3% BSA for 0.5 hour before primary antibody at 1:25 (caption M00728-3). If diffuse staining increases with antibody concentration, compare a dilution series while keeping retrieval, exposure and chromogen development consistent (standard IHC practice). Use the appropriate endogenous peroxidase and biotin controls for the chosen detection system, since the selected example used a biotinylated secondary antibody (caption M00728-3; standard IHC practice).
How should I quantify SMAD1 IHC across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, because SMAD1 can be nuclear or cytoplasmic (UniProt Q15797; HPA tissue IHC). Report the percentage of positive cells and an H-score for each compartment, using the same intensity thresholds across matched slides (standard IHC scoring practice). Normalise counts to the number of eligible cells in the annotated region; if measuring positive cell density, divide by analysed tissue area in mm² (standard IHC scoring practice). Exclude folds, tissue loss and necrotic regions by a preset rule, and keep retrieval and chromogen development consistent across comparisons (standard IHC practice).
How can I separate credible SMAD1 signal from staining artefacts?
Credible SMAD1 staining can occur in cytoplasm and nuclei, and HPA reports high glandular cell staining in epididymis and stomach (UniProt Q15797; HPA tissue IHC). Compare signal with the intended cell type and intact morphology; staining confined to section edges, folds or necrotic areas warrants an artefact check (standard IHC practice). Test suspicious chromogen deposits with a no primary control and the appropriate endogenous enzyme control for the detection system (standard IHC practice). HPA rates its tissue IHC evidence as Approved but notes low consistency with RNA expression, so interpret an isolated strong field cautiously (HPA tissue IHC).
Boster reagents
Best SMAD1 / SMAD family member 1 IHC Antibodies
The catalog shows human paraffin-section IHC and human cell IF images (catalog image captions); one IF/ICC antibody also lists mouse reactivity (M00728-1 applications/reactivity).
Real IHC data
Anti-SMAD1 Antibody
Cat # M00728-3
Real IHC data
Anti-Smad1 Rabbit Monoclonal Antibody
Cat # M00728
Real IHC data
Anti-Smad1 Rabbit Monoclonal Antibody
Cat # M00728-1
M00728-3 shows IHC in formaldehyde-fixed human skeletal muscle paraffin sections (M00728-3 image caption); M00728 shows IHC in human colon paraffin sections, with fixative unreported (M00728 image caption). M00728-1 shows human kidney paraffin-section staining and an IF image at 1:50, although IHC is absent from its listed applications and the kidney fixative is unreported (M00728-1 image captions/applications).
Which to pick: For tissue IHC, choose M00728-3: its IHC-P application and skeletal muscle caption document formaldehyde fixation, citrate retrieval at pH 6, and a 1:25 primary dilution (M00728-3 applications/image caption). M00728 is another human paraffin-section IHC option, but its colon caption does not report a fixative (M00728 applications/image caption). For IF/ICC or a human-and-mouse study, choose the rabbit monoclonal M00728-1 based on its applications and reactivity; IHC is not listed for this SKU despite its human kidney staining caption (M00728-1 catalog applications/reactivity/image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q15797 (SMAD1_HUMAN, SMAD family member 1).
- Human Protein Atlas. SMAD1 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. SMAD1 subcellular location (ICC-IF): Localized to the nucleoplasm and cytosol..
- Human Protein Atlas. SMAD1 antibody validation summary (1 antibodies).
- Expression of BMP-4 and Smad1 in patients with Hirschsprung disease and its clinical significance. Experimental and therapeutic medicine 2019 — PMC6566125.
- Smad1 expression in follicular lymphoma. Journal of pathology and translational medicine 2015 — PMC4440936.
- Spatial regulation of bone morphogenetic proteins (BMPs) in postnatal articular and growth plate cartilage. PloS one 2017 — PMC5414995.
- BMP9 attenuates microgravity-related disuse osteoporosis by modulating TGFβ and BMP signaling. NPJ microgravity 2025 — PMC12316925.
- PubMed PMID:8673135 — UniProt-cited evidence.
- PubMed PMID:8637600 — UniProt-cited evidence.
- PubMed PMID:8653785 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for SMAD1 (SMAD family member 1). Expected localisation Cytoplasmic and nuclear staining (HPA tissue IHC). Antigen retrieval: Citrate pH 6 HIER, heat-mediated (datasheet M00728-3). Validated IHC antibody: M00728-3 at 1:25 (the product's own IHC validation image is shown). Controls (HPA): positive Epididymis (Glandular cells); negative Adrenal gland. IHC-P workflow on paraffin sections. Protocol steps: 1. Sample: Formaldehyde-fixed, paraffin-embedded human skeletal muscle tissue (datasheet M00728-3); 2. Fixation: Image formalin-fixed; duration unreported (datasheet M00728-3); 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: Citrate pH 6 (datasheet M00728-3); 20 min, 95–100 °C (standard); 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: Mouse monoclonal (clone 1356CT119.18.55) anti-SMAD1, 1:25 (datasheet M00728-3); 9. Primary incubation: 1 hours at 37°C (datasheet M00728-3). Watch for: Fixation: Formaldehyde-fixed paraffin sections were used (selected-SKU IHC image M00728-3); Caveat: Staining has low consistency with RNA expression (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope coverage is unspecified (UniProt); Regulation: BMP signaling drives nuclear translocation (UniProt). Evidence: UniProt Q15797, HPA tissue IHC · Approved, HPA ICC-IF · nucleoplasm and cytosol., Datasheet M00728-3, PMC6566125, PMC12316925. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/SMAD1/immunohistochemistry-ihc-guide.