This website uses cookies to ensure you get the best experience on our website.
- Table of Contents
ISL1 / Insulin gene enhancer protein ISL-1 · IHC design guide
Design Immunohistochemistry for ISL1
Plan ISL1 chromogenic IHC in paraffin sections around its nuclear staining pattern and the cell populations reported as positive (HPA tissue IHC). The guide covers fixation, staining controls and interpretation of sparse positive cells (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
ISL1 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 | Nuclear staining in a few tissues (HPA tissue IHC) | |
| Staining pattern | Nuclear staining in selected cell populations (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A02969-3) | |
| Positive control | Adrenal gland+4 more · see all | |
| 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 A02969-3); verify before use. | |
| Caveat | Sparse positive cells may be missed in sections (HPA tissue IHC) | |
| Regulation | Expression varies by cell type (HPA tissue IHC) | |
| Isoform / epitope | No isoforms or cleavage products annotated (UniProt) |
Section 1
Recommended ISL1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by published ISL1 IHC methods for neuroendocrine tumors and neural tissue (PMC7665972; PMC4898681).
| Sample | Paraffin-embedded mouse brain tissue; fixative not specified (datasheet A02969-3) |
| Fixation | Image fixative and duration unreported (datasheet A02969-3); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A02969-3); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A02969-3) |
| Primary antibody | Rabbit anti-ISL1, 2-5 μg/ml (datasheet A02969-3) |
| Primary incubation | Overnight at 4 °C (datasheet A02969-3) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A02969-3) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | ISL1-positive staining in glandular cells of adrenal gland (HPA tissue IHC: Medium). HPA tissue profile: Nuclear expression in few tissues. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA retrieval at pH 8.0 for the catalog antibody (datasheet A02969-3); the tumor study used Ultra CC1 buffer (PMC7665972).
Section 2
What Is the Expected ISL1 Staining Pattern?
ISL1 is a nuclear transcription factor with no transmembrane segment (UniProt P61371). In paraffin-section IHC, expect staining in nuclei of selected cells, including adrenal glandular cells, kidney tubular cells and testicular Leydig cells; HPA reports medium staining in each (HPA tissue IHC). HPA describes expression in few tissues, but rates its tissue IHC evidence Approved, pending external verification (HPA tissue IHC).
| Distinct nuclear stain in a subset of adrenal glandular cells, kidney tubular cells or testicular Leydig cells. | This fits the reported compartment and cell distribution; medium staining is reported for these cells (HPA tissue IHC; UniProt P61371). Score the named cell population and its nuclear signal. HPA's Approved rating is pending external verification, so confirm the pattern with controls (HPA tissue IHC; standard IHC practice). |
| Predominantly cytoplasmic, membranous or extracellular chromogen, with little nuclear staining. | That distribution conflicts with the expected nuclear IHC profile and the absence of a transmembrane segment (HPA tissue IHC; UniProt P61371). Treat it as suspect staining; review morphology, the no-primary control and detection conditions before assigning ISL1 positivity (standard IHC practice). |
| Stain appears in cells expected to be negative, such as adipocytes in adipose tissue or hematopoietic cells in bone marrow. | Both named populations were not detected in HPA tissue IHC (HPA tissue IHC). Check whether signal follows the cell nuclei; unexpected staining can reflect antibody cross-reactivity or endogenous detection activity (standard IHC practice). A negative reference is a comparison, not proof that every specimen must be unstained. |
| Diffuse chromogen obscures nuclei across multiple cell types or tissue regions. | A widespread haze cannot establish the selective nuclear pattern reported for ISL1 (HPA tissue IHC). Compare with a no-primary control, inspect reagent background and adjust blocking, washing or detection conditions as indicated (standard IHC practice). Do not score obscured nuclei as positive. |
| No nuclear signal in an adrenal gland section containing identifiable glandular cells. | HPA reports medium staining in adrenal glandular cells, so this is a useful positive-reference failure to investigate (HPA tissue IHC). Verify that the intended cells are present and review antibody concentration, retrieval and detection with the catalog IHC-P protocol (standard IHC practice); HPA does not establish ISL1-specific fixation sensitivity. |
💡Expected ISL1 appearanceCall a result positive when the relevant cells show interpretable nuclear chromogen, with medium staining reported in selected HPA populations; diffuse background or chiefly nonnuclear staining is suspect (HPA tissue IHC; UniProt P61371; standard IHC practice).
| Compartment and cell distribution (UniProt P61371; HPA tissue IHC) | ISL1 is nuclear, while HPA reports expression in few tissues and medium staining in selected cell populations. Judge nuclear signal within the named cells; a tissue-wide positive/negative label can conceal a small positive population (HPA tissue IHC). |
| Evidence strength and antibody validation (HPA tissue IHC; HPA antibodies) | HPA's tissue IHC rating is Approved with external verification pending. Its IHC-Approved antibody is HPA057416; HPA048613 is ICC-Approved with no IHC status supplied (HPA antibodies). Validation of one antibody or application does not establish the other's IHC performance. |
| Antigen retrieval and detection setup (standard IHC practice) | Follow the catalog antibody's IHC-P instructions and assess changes against positive and negative controls (standard IHC practice). The supplied HPA and UniProt records give no ISL1-specific retrieval condition or fixation-effect evidence; neither source supports predicting a rescue from altered retrieval. |
| Situation | Likely cause | Next action |
|---|---|---|
| Adrenal glandular nuclei are blank (HPA tissue IHC). | A missed target cell population or an unsuccessful staining run are possibilities (standard IHC practice). | Confirm cell identity and section quality, then check the catalog antibody's IHC-P instructions, retrieval, dilution and detection controls (standard IHC practice). |
| Only cytoplasmic or edge staining appears. | The location conflicts with nuclear ISL1 and HPA's nuclear IHC profile (UniProt P61371; HPA tissue IHC). | Compare with a no-primary control and examine section edges and morphology; score only convincing nuclear staining in the relevant cells (standard IHC practice). |
| Adipocytes or bone-marrow hematopoietic cells stain strongly. | HPA reports these cells as not detected; cross-reactivity or endogenous detection activity may account for unexpected signal (HPA tissue IHC; standard IHC practice). | Check nuclear localisation, run a no-primary control and review blocking or endogenous-activity controls appropriate to the detection chemistry (standard IHC practice). |
| Weak haze makes nuclear scoring uncertain. | Background or insufficient separation between signal and counterstain may obscure nuclei (standard IHC practice). | Compare control sections, review washing and blocking, and adjust counterstain or detection conditions using the IHC-P workflow (standard IHC practice). |
| A tissue called negative contains a few stained nuclei. | HPA's profile is selective, and its listed cell-level observations do not make every cell in a tissue equivalent (HPA tissue IHC). | Identify the stained cell type and compare its nuclear pattern with HPA's cell-level entries before interpreting the result (HPA tissue IHC; standard IHC practice). |
| IF/ICC question: should extranuclear fluorescence be expected? | HPA reports mainly nucleoplasmic signal, with additional nuclear-speckle and mitochondrial localisation in ICC-IF (HPA subcellular). | Interpret that observation within the separate IF/ICC application; it does not override the nuclear expectation for paraffin-section IHC, and HPA's ICC approval is antibody-specific (HPA tissue IHC; HPA antibodies). |
Experiment evidence
IHC & IF images showing ISL1 staining
A02969-3 · IHCIHC analysis of Islet 1/ISL1 using anti-Islet 1/ISL1 antibody (A02969-3). Islet 1/ISL1 was detected in a paraffin-embedded section of mouse
A02969-3 · IHCIHC analysis of Islet 1/ISL1 using anti-Islet 1/ISL1 antibody (A02969-3). Islet 1/ISL1 was detected in a paraffin-embedded section of rat br
A02969-3 · IFIF analysis of Islet 1/ISL1 using anti-Islet 1/ISL1 antibody (A02969-3) and anti-Beta Tubulin antibody (M01857-3). Islet 1/ISL1 was detected
A02969-1 · IHCIHC analysis of Islet 1 using anti-Islet 1 antibody (A02969-1). Islet 1 was detected in paraffin-embedded section of human mammary cancer ti
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000016082-ISL1/tissue/cerebral+cortex#imid_16342323
HPA · CaudateHuman Protein Atlas IHC, Caudate. Source: https://www.proteinatlas.org/ENSG00000016082-ISL1/tissue/basal+ganglia#imid_16342325
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000016082-ISL1/tissue/colon#imid_16342265
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000016082-ISL1/tissue/liver#imid_16342250
HPA · ICC-IF HeLaHuman Protein Atlas immunofluorescence, HeLa, antibody HPA048613; green = ISL1, blue = nucleus, red = microtubules.
HPA · ICC-IF HeLaHuman Protein Atlas immunofluorescence, HeLa, antibody HPA048613; green = ISL1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for ISL1 IHC & IF
🧪Run adrenal gland first and expect staining in glandular cells (HPA: adrenal gland glandular cells, Medium). Use adipose tissue as the negative tissue, where adipocytes are not detected (HPA: adipose tissue adipocytes, Not detected); on the positive slide, cells without specific staining should lack nuclear signal above control background (UniProt P61371: Nucleus).
Positive control tissue: Adrenal gland (Glandular cells, HPA Medium)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show ISL1 in HeLa, SH-SY5Y, U2OS, with annotated localisation: Nucleoplasm (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and nonimmune IgG matched to the primary antibody’s host species and clonality; confirm specificity with matched ISL1 knockout tissue when available (standard IHC control practice). For DAB detection, quench endogenous peroxidase and assess residual background on the adrenal slide (standard chromogenic IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported, and the selected A02969-3 paraffin-section caption does not state a fixative (selected-SKU IHC caption: fixative unreported). That caption uses heat-mediated retrieval in EDTA at pH 8.0, but does not establish that retrieval is required (selected-SKU IHC caption: EDTA retrieval). The supplied evidence does not establish whether frozen sections or IF are easier; assess adrenal pigment and background when scoring nuclear staining (HPA: adrenal gland glandular cells, Medium; UniProt P61371: Nucleus; standard IHC practice).
HPA tissue IHC evidence for ISL1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Pending external verification.). 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 |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | Medium | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Medium | Protein (IHC) | HPA → |
| Caudate | Glial cells | Medium | Protein (IHC) | HPA → |
| Cerebellum | Cells in molecular layer | Medium | Protein (IHC) | HPA → |
| Fallopian tube | Glandular cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Cervix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Colon | Endothelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced ISL1 IHC Tips
Troubleshoot ISL1 staining by checking retrieval, nuclear localisation and cell identity before interpreting chromogenic signal (UniProt P61371; HPA tissue IHC).
Which retrieval should I start with for weak ISL1 staining in paraffin sections?
Start with heat-mediated antigen retrieval in EDTA at pH 8.0 for paraffin sections stained with A02969-3 (datasheet A02969-3). The reported staining used 2 μg/ml primary antibody overnight at 4°C, so keep those conditions consistent while assessing retrieval (datasheet A02969-3). Compare a known nuclear-positive area across sections heated for different durations, keeping section thickness and detection conditions consistent (standard IHC practice; UniProt P61371 localisation). If nuclear signal remains weak, test another retrieval buffer or pH as a fallback on matched sections and compare background alongside signal (standard IHC practice). Judge improvement by sharper nuclear staining, not by increased diffuse chromogen (UniProt P61371 localisation; standard IHC practice).
Could fixation explain weak or uneven ISL1 nuclear staining?
The A02969-3 tissue image documents a paraffin-embedded mouse brain section but does not state its fixative or fixation duration (datasheet A02969-3). Target-specific fixation sensitivity is therefore unknown; the HPA tissue staining pattern does not establish which fixation conditions preserve this antibody’s epitope (datasheet A02969-3; HPA tissue IHC). Record the fixative and fixation duration for each specimen, then compare similarly processed sections using the same pH 8.0 EDTA retrieval (standard IHC practice; datasheet A02969-3). Check whether signal loss tracks processing batches and whether tissue morphology supports reliable nuclear scoring (standard IHC practice). Use a matched positive control to assess the staining run before attributing a negative specimen to biology (standard IHC practice).
How should I assess cytoplasmic staining when ISL1 is expected in nuclei?
Score nuclear signal first: ISL1 is annotated as nuclear, and HPA describes mainly nucleoplasmic localisation (UniProt P61371 localisation; HPA subcellular). HPA also reports nuclear speckles and mitochondria in cell imaging, so an extra-nuclear signal warrants context and independent validation rather than automatic acceptance in tissue IHC (HPA subcellular; standard IHC practice). Compare nuclei within the same cell population and inspect the counterstain to separate nuclear chromogen from adjacent cytoplasm (standard IHC practice). The A02969-3 paraffin-section example used EDTA at pH 8.0; repeat its documented retrieval before changing antibody concentration to investigate diffuse signal (datasheet A02969-3). Report nuclear and non-nuclear staining separately (standard IHC practice).
Can an unreported isoform or epitope explain discordant ISL1 staining?
The supplied ISL1 record lists one 1–349 chain and no annotated isoforms, so an isoform-specific explanation lacks support here (UniProt P61371). It places LIM zinc-binding domains at residues 17–70 and 79–133, but the A02969-3 caption does not map the antibody epitope (UniProt P61371; datasheet A02969-3). Do not assume retrieval exposes either domain or that a missed signal identifies a sequence variant (standard IHC practice). Compare the same cell population with an independently validated antibody of known epitope, if available, and document agreement at the nuclear level (standard IHC practice; UniProt P61371 localisation). The record lists no specific modified residues; that annotation alone cannot establish epitope stability after processing (UniProt P61371).
How can I use IF to investigate an ambiguous chromogenic ISL1 result?
For a separate IF experiment, pair ISL1 with a validated marker for the expected cell population, such as the neuronal or retinal ganglion cell populations described for ISL1 (UniProt P61371 tissue specificity and function; standard IF practice). Choose spectrally separated fluorophores and assess unstained tissue autofluorescence before selecting the ISL1 channel; a far-red channel can help when shorter-wavelength autofluorescence is strong (standard IF practice). ISL1 is nuclear and has no transmembrane segment, so permeabilise fixed cells or tissue sufficiently for nuclear access while preserving morphology (UniProt P61371 topology and localisation; standard IF practice). Include single-label and secondary-only controls to assess bleed-through and background (standard IF practice). The A02969-3 caption establishes paraffin-section IHC conditions, not an IF dilution or fixation method (datasheet A02969-3).
What should I check when DAB obscures ISL1-positive nuclei?
The A02969-3 image used 10% goat serum blocking, 2 μg/ml primary antibody overnight at 4°C, and DAB development (datasheet A02969-3). Begin by comparing matched sections with and without primary antibody to identify detection-related background (standard IHC practice). Apply an endogenous peroxidase block and control DAB development time as general chromogenic IHC steps, especially when diffuse brown signal masks nuclei (standard IHC practice; UniProt P61371 localisation). If primary-dependent background remains, titrate antibody concentration and blocking conditions on matched sections while retaining the documented EDTA pH 8.0 retrieval (standard IHC practice; datasheet A02969-3). Accept a change only when nuclear contrast improves without losing expected positive cells (standard IHC practice; HPA tissue IHC).
How should I score ISL1 staining across heterogeneous tissue regions? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and anatomical region before scoring because HPA reports nuclear expression in few tissues and differing cell types (HPA tissue IHC). For chromogenic sections, report the percentage of positive nuclei and, when intensity is reproducible, an H-score based on nuclear staining categories (standard IHC practice; UniProt P61371 localisation). Alternatively, report ISL1-positive nuclei per mm² within a predefined region, alongside total nuclei per mm² to reveal changes in cellularity (standard IHC practice). Normalise positive-cell counts to all evaluable nuclei of the specified cell type, using the same positivity threshold and counterstain criteria across sections (standard IHC practice). Exclude damaged tissue and document how regions were selected (standard IHC practice).
When is an apparent ISL1-positive cell more likely to be artefact?
A convincing result places chromogen over intact nuclei in the relevant cell population, consistent with ISL1 nuclear localisation and the tissue context (UniProt P61371 localisation and tissue specificity; standard IHC practice). Be cautious with staining confined to cut edges, necrotic areas or damaged cells, where morphology makes localisation unreliable (standard IHC practice). Treat widespread cytoplasmic precipitate or signal in a mismatched cell population as a prompt to inspect controls and reassess specificity (UniProt P61371 localisation; standard IHC practice). A no-primary section helps reveal endogenous enzyme or detection-system signal, while matched positive tissue tests whether the staining run worked (standard IHC practice). HPA’s tissue IHC reliability is marked Approved with external verification pending, so use its pattern as supporting context (HPA tissue IHC).
Boster reagents
Best ISL1 / Insulin gene enhancer protein ISL-1 IHC Antibodies
A02969-3 has IHC images in mouse and rat brain and IF images in A549 cells and mouse and rat brain (catalog image captions); A02969-1 has human mammary cancer IHC (catalog image caption).
Real IHC data
Anti-Islet 1/ISL1 Antibody ®
Cat # A02969-3
Real IHC data
Anti-Islet 1/ISL1 Antibody ®
Cat # A02969-1
A02969-3 will render with its mouse brain paraffin-section IHC figure; its additional captions show rat brain IHC and IF in A549 cells and mouse and rat brain (A02969-3 image captions). A02969-1 will render with its human mammary cancer paraffin-section IHC figure (A02969-1 IHC caption).
Which to pick: For human mammary cancer tissue IHC, choose A02969-1; its figure used citrate retrieval at pH 6 for 20 minutes and 1 μg/ml primary antibody (A02969-1 IHC caption). For IF/ICC or mouse and rat brain IHC, choose A02969-3: it lists IF and ICC, reports Human, Mouse and Rat reactivity, and its brain IHC captions used EDTA retrieval at pH 8 and 2 μg/ml primary antibody (A02969-3 applications, reactivity and IHC captions). Both IHC figures show paraffin sections, and neither caption reports the fixative (A02969-1 and A02969-3 IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P61371 (ISL1_HUMAN, Insulin gene enhancer protein ISL-1).
- Human Protein Atlas. ISL1 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. ISL1 subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to the nuclear speckles and mitochondria..
- Human Protein Atlas. ISL1 antibody validation summary (2 antibodies).
- Age-Characteristic Changes of Glucose Metabolism, Pancreatic Morphology and Function in Male Offspring Rats Induced by Prenatal Ethanol Exposure. Frontiers in endocrinology 2019 — PMC6369175.
- Clinical Routine Application of the Second-generation Neuroendocrine Markers ISL1, INSM1, and Secretagogin in Neuroendocrine Neoplasia: Staining Outcomes and Potential Clues for Determining Tumor Origin. Endocrine pathology 2020 — PMC7665972.
- The Role of ISL1 and LHX5 LIM Homeobox Genes in Bladder Tumourigenesis. The Malaysian journal of medical sciences : MJMS 2020 — PMC7053544.
- Celsr3 and Fzd3 Organize a Pioneer Neuron Scaffold to Steer Growing Thalamocortical Axons. Cerebral cortex (New York, N.Y. : 1991) 2016 — PMC4898681.
- PubMed PMID:7907017 — UniProt-cited evidence.
- PubMed PMID:7912209 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for ISL1 (Insulin gene enhancer protein ISL-1). Expected localisation Nuclear staining in a few tissues (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A02969-3). Validated IHC antibody: A02969-3 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded mouse brain tissue; fixative not specified (datasheet A02969-3); 2. Fixation: Image fixative and duration unreported (datasheet A02969-3); 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: EDTA pH 8.0 (datasheet A02969-3); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A02969-3); 8. Primary antibody: Rabbit anti-ISL1, 2-5 μg/ml (datasheet A02969-3); 9. Primary incubation: Overnight at 4 °C (datasheet A02969-3). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific). Selected-image fixative and duration unreported (datasheet A02969-3); verify before use.; Caveat: Sparse positive cells may be missed in sections (HPA tissue IHC); Isoform / epitope: No isoforms or cleavage products annotated (UniProt); Regulation: Expression varies by cell type (HPA tissue IHC). Evidence: UniProt P61371, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to the…, Datasheet A02969-3, PMC7665972, PMC4898681. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/ISL1/immunohistochemistry-ihc-guide.