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PREX1 / Phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 1 protein · IHC design guide
Design Immunohistochemistry for PREX1
Plan PREX1 IHC-P around cytoplasmic staining in immune and neuronal cells (HPA tissue IHC). This guide covers fixation, antibody use and cell-type controls for paraffin sections (datasheet A03098-1; HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
PREX1 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 staining; membrane staining in Bergmann glia (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining in immune and neuronal cells (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6 HIER, heat-mediated (datasheet A03098-1) | |
| Positive control | Cerebellum+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Formalin-fixed paraffin sections were used (selected-SKU IHC image A03098-1); keep fixation consistent (standard IHC practice; not target-specific) | |
| Caveat | Presumed off-target binding may mimic PREX1 staining (HPA tissue IHC) | |
| Regulation | Expression is highest in leukocytes and brain (UniProt) | |
| Isoform / epitope | 3 isoforms; epitope conservation is unknown (UniProt) |
Section 1
Recommended PREX1 IHC & IF Protocols
The catalog antibody protocol (datasheet: A03098-1) is followed by published PREX1 IHC protocols for glioblastoma tissue microarrays (PMC5352422) and human melanoma sections (PMC5065759).
| Sample | Formaldehyde-fixed, paraffin-embedded human brain tissue (datasheet A03098-1) |
| Fixation | Image formalin-fixed; duration unreported (datasheet A03098-1); 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 A03098-1); 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 | Rabbit anti-PREX1, 1:10-1:50 (datasheet A03098-1) |
| Primary incubation | 1 hours at 37°C (datasheet A03098-1) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | PREX1-positive staining in bergmann glia - cytoplasm/membrane of cerebellum (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in several tissues, most abundant in immune and neuronal cells. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6 heat retrieval (datasheet: A03098-1; PMC5352422). Consider EDTA heat retrieval for melanoma sections (PMC5065759).
Section 2
What Is the Expected PREX1 Staining Pattern?
PREX1 should appear mainly in the cytoplasm, with some plasma membrane association; it has no transmembrane segment (UniProt Q8TCU6 localisation and topology). In paraffin tissue sections, expect prominent staining in lung macrophages and cerebellar Bergmann glia, with weaker or less widespread staining in other listed cell populations (HPA tissue IHC: High in both; overall reliability: Supported). Interpret the cell type and compartment together because HPA reports presumed off-target binding (HPA tissue IHC reliability description).
| Cytoplasmic staining in lung macrophages or cytoplasmic and membrane staining in cerebellar Bergmann glia. | These are the clearest listed positive patterns: each is High in HPA tissue IHC. PREX1 is mainly cytosolic, with some plasma membrane association (UniProt Q8TCU6 localisation). Judge staining within the annotated cells, since HPA reports only medium consistency with RNA and notes presumed off-target binding (HPA tissue IHC reliability description). |
| Predominantly nuclear staining, with little corresponding cytoplasmic signal in the expected positive cells. | A nuclear dominant pattern does not fit the supplied localisation evidence: UniProt places PREX1 mainly in cytosol and partly at the plasma membrane, while HPA tissue IHC describes cytoplasmic expression (UniProt Q8TCU6 localisation; HPA tissue IHC profile). Treat this as a possible artefact and reassess staining controls before assigning it to PREX1 (general IHC practice). |
| Strong staining in an annotated cell type where HPA reports PREX1 as not detected, such as adipocytes in adipose tissue. | That pattern conflicts with the listed cell specific observation (HPA tissue IHC: adipocytes, Not detected). Cross-reactivity or endogenous chromogenic detection activity are possible explanations, rather than evidence that PREX1 is present there (general IHC practice). HPA itself notes presumed off-target binding in its tissue assessment (HPA tissue IHC reliability description). |
| Diffuse chromogen across cells and surrounding tissue, without a discernible cytoplasmic pattern. | A uniform deposit cannot establish cell specific PREX1 staining; the reference pattern is cytoplasmic in several tissues and most abundant in immune and neuronal cells (HPA tissue IHC profile). Consider background from detection reagents or inadequate blocking, and inspect a negative control alongside the section (general IHC practice). |
| No staining in lung macrophages or cerebellar Bergmann glia on an otherwise evaluable section. | Both populations are listed as High positives (HPA tissue IHC: lung macrophages and cerebellar Bergmann glia). First check section quality and the antibody and chromogen detection steps using appropriate controls (general IHC practice). A failed run is one possibility; the HPA pattern alone does not identify its cause or establish a PREX1 specific fixation effect. |
💡Expected PREX1 appearanceCall the IHC result consistent with PREX1 when identifiable lung macrophages show strong cytoplasmic staining or cerebellar Bergmann glia show strong cytoplasmic and membrane staining (HPA tissue IHC: both High; UniProt Q8TCU6 localisation); isolated nuclear signal or widespread staining in HPA negative cell types is suspect (HPA tissue IHC profile and negatives; general IHC practice).
| Cellular distribution | PREX1 is mainly cytosolic, although some is apparently associated with the plasma membrane, and no transmembrane segment is listed (UniProt Q8TCU6 localisation and topology). Thus cytoplasm should anchor interpretation; the membrane component can support a result in the right cells, especially Bergmann glia, whose HPA annotation includes cytoplasm and membrane (HPA tissue IHC: cerebellum). |
| Tissue and cell context | HPA lists High staining in lung macrophages and cerebellar Bergmann glia; Medium staining in bone marrow hematopoietic cells, lymph node germinal center cells, spleen red pulp cells, and late spermatids; and Low staining in tonsil germinal center cells (HPA tissue IHC). Compare like cell types rather than treating every cell in a positive tissue as positive (general IHC practice). |
| Isoform and epitope coverage | UniProt lists 3 PREX1 isoforms, but the supplied record gives no antibody epitope or isoform coverage (UniProt Q8TCU6 isoforms; supplied HPA antibody summary). A staining difference cannot be assigned to a particular isoform from these sources. Interpret the observed compartment and annotated cell type before making any isoform claim (UniProt Q8TCU6 localisation; HPA tissue IHC). |
| Processing and antibody validation | UniProt lists no signal peptide or propeptide and describes a 1–1659 chain (UniProt Q8TCU6 processing). The supplied HPA antibody, HPA001927, has IHC status Supported; the tissue assessment reports medium consistency with RNA and presumed off-target binding (HPA antibody summary; HPA tissue IHC reliability description). These records support cautious pattern comparison, not a claim that every chromogenic signal is specific. |
| Does IF/ICC show the same pattern? | HPA ICC-IF places PREX1 in vesicles (Approved) and cytosol (Supported), with images listed for A-431, U-251MG, and U2OS (HPA subcellular ICC-IF). This supports a cytosolic component across applications, while the vesicle annotation comes from ICC-IF rather than tissue IHC. Evaluate paraffin tissue staining against the tissue IHC cell annotations and UniProt localisation (HPA tissue IHC; UniProt Q8TCU6). |
| Situation | Likely cause | Next action |
|---|---|---|
| A listed High positive cell population has no visible chromogen (HPA tissue IHC: lung macrophages or Bergmann glia). | Section quality, primary antibody application, or detection failure may explain a blank run (general IHC practice); no PREX1 specific fixation sensitivity is supplied. | Review a positive control section, tissue morphology, primary antibody application, and detection reagents; repeat only the step implicated by those checks (general IHC practice). |
| Nuclear staining dominates while the expected cytoplasm is clear. | The compartment conflicts with the mainly cytosolic PREX1 assignment and HPA's cytoplasmic tissue profile (UniProt Q8TCU6 localisation; HPA tissue IHC profile). | Compare an antibody omitted control and a listed positive tissue, then assess whether the nuclear signal follows the detection system rather than the expected cells (general IHC practice; HPA tissue IHC positives). |
| Strong chromogen appears in HPA negative cells, including adipocytes in adipose tissue. | Cross-reactivity or endogenous detection activity is plausible; HPA notes presumed off-target binding (general IHC practice; HPA tissue IHC reliability description). | Check a primary antibody omitted control and appropriate blocking for the chromogenic system; score the annotated cell type separately from nearby positive cells (general IHC practice). |
| A uniform haze obscures boundaries and prevents cell level scoring. | Nonspecific reagent binding or excess chromogen development can obscure a cellular pattern (general IHC practice). | Review blocking, reagent washes, detection timing, and the negative control; accept a result only when cellular staining can be distinguished from background (general IHC practice). |
| Cytoplasm stains clearly, but little membrane accent is visible. | That can still fit PREX1: UniProt describes it as mainly cytosolic, with only some amount apparently associated with plasma membrane (UniProt Q8TCU6 localisation). | Score the cytoplasmic pattern in the correct annotated cells first; use the Bergmann glia membrane annotation as supporting context, not a required feature in every tissue (HPA tissue IHC: cerebellum; general IHC practice). |
| A tissue labelled positive appears mixed, with many unstained neighboring cells. | HPA's levels refer to named cell populations, such as macrophages in lung and germinal center cells in lymph node, rather than every cell in those tissues (HPA tissue IHC positives). | Locate and score the annotated population against its neighboring cells and confirm that the counterstain preserves cell identification (HPA tissue IHC positives; general IHC practice). |
Experiment evidence
IHC & IF images showing PREX1 staining
A03098-1 · IHCA03098-1 staining PREX1 in human brain tissue sections by Immunohistochemistry (IHC-P -paraformaldehyde-fixed, paraffin-embedded sections).
A03098-1 · IHCPREX1 Antibody (C-term) immunohistochemistry analysis in formalin fixed and paraffin embedded human brain tissue followed by peroxidase conj
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000124126-PREX1/tissue/cerebral+cortex#imid_1121464
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000124126-PREX1/tissue/colon#imid_1116926
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000124126-PREX1/tissue/liver#imid_1116911
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000124126-PREX1/tissue/kidney#imid_1116912
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA001927; green = PREX1, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA001927; green = PREX1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for PREX1 IHC & IF
🧪Run cerebellum first: Bergmann glia should show cytoplasmic and membrane staining (HPA: Bergmann glia, High). Use adipose tissue adipocytes as the negative tissue (HPA: adipocytes, Not detected); neighboring non-Bergmann cells should lack comparable staining, but HPA does not establish them as negative controls (HPA: Bergmann glia, High).
Positive control tissue: Cerebellum (Bergmann glia - cytoplasm/membrane, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show PREX1 in A-431, U-251MG, U2OS, with annotated localisation: Vesicles (approved), Cytosol (supported) (HPA subcellular).
Technical controls: Include no-primary/secondary-only and host-species- and isotype-matched controls, plus PREX1-knockout tissue or peptide blocking if the immunizing peptide is available (standard IHC controls). Because the caption uses a biotinylated secondary, check for endogenous biotin in cerebellum and block it if present (A03098-1 caption: biotinylated secondary; standard IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected SKU's fixative field is unreported (A03098-1 caption metadata: fixative not stated). The paraffin-section example uses heat retrieval in citrate buffer at pH 6, but does not establish that retrieval is required (A03098-1 caption: citrate retrieval). IHC-P has a tissue example, while an advantage for frozen sections or IF is unreported (A03098-1 caption: tissue IHC-P; HPA: ICC-IF subcellular images); endogenous biotin may complicate the biotin-based cerebellum stain (A03098-1 caption: biotinylated secondary; standard IHC practice).
HPA tissue IHC evidence for PREX1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — Medium consistency between antibody staining and RNA expression data. Presumed off target binding observed and disregarded. 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 |
|---|---|---|---|---|
| Cerebellum | Bergmann glia - cytoplasm/membrane | High | Protein (IHC) | HPA → |
| Lung | Macrophages | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Medium | Protein (IHC) | HPA → |
| Lymph node | Germinal center cells | Medium | Protein (IHC) | HPA → |
| Spleen | Cells in red pulp | Medium | 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 → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced PREX1 IHC Tips
Troubleshoot PREX1 staining in paraffin sections by checking retrieval, cell type, compartment, and controls before comparing signal across samples.
Which retrieval conditions should I try first for PREX1 IHC on paraffin sections?
Start with heat-mediated citrate buffer at pH 6 for antigen retrieval (datasheet A03098-1). Run a known positive section alongside each retrieval trial; human brain tissue was stained with this catalog antibody after citrate retrieval (datasheet A03098-1). If staining is weak, adjust heating duration or cooling conditions on serial sections while keeping buffer and detection conditions constant (standard IHC practice). Judge improvement in expected immune or neuronal cells, rather than by overall darkness, because cytoplasmic expression is most abundant in those cells (HPA: tissue profile). Excess retrieval can damage morphology and make chromogenic signal harder to assign to individual cells (standard IHC practice).
How should I troubleshoot weak PREX1 staining when fixation varies between samples?
PREX1-specific sensitivity to fixation is unknown from the supplied evidence, so treat fixation differences as an experimental variable (evidence scope: no target-specific fixation comparison supplied). Record fixative, fixation duration, processing history, and section age for each specimen before comparing staining (standard IHC practice). Test matched sections together with the same citrate buffer at pH 6 and identical detection settings (datasheet A03098-1; standard IHC practice). Include a positive control on every run, and assess cellular morphology as well as chromogenic signal (standard IHC practice). Do not infer fixation tolerance from the tissue-expression profile or PREX1’s cytosolic location (HPA: tissue profile; UniProt Q8TCU6: subcellular location).
What staining pattern is plausible for PREX1 in tissue sections?
Expect predominantly cytoplasmic signal, with possible membrane-associated signal: PREX1 is mainly cytosolic and some protein associates with the plasma membrane (UniProt Q8TCU6: subcellular location). The tissue atlas reports cytoplasmic expression in several tissues, most abundantly in immune and neuronal cells (HPA: tissue profile). Examine cell boundaries and the hematoxylin counterstain before calling a narrow peripheral rim membrane staining (standard IHC practice). PREX1 has no transmembrane segment, so membrane association does not imply that it spans the membrane (UniProt Q8TCU6: topology). Score unexpected nuclear-only staining separately and check controls before accepting it as PREX1 (UniProt Q8TCU6: subcellular location; standard IHC practice).
Could isoforms or phosphorylation explain inconsistent PREX1 staining?
PREX1 has 3 annotated isoforms and reported phosphoserines at positions 319, 1001, 1195, and 1200 (UniProt Q8TCU6: isoforms; modified residues). The supplied evidence does not identify this antibody’s epitope, so its recognition of individual isoforms or modified protein cannot be assigned (evidence scope: epitope not supplied). Ask for epitope information and compare it with isoform sequences before claiming isoform specificity (standard antibody-validation practice). Keep fixation, citrate retrieval at pH 6, and detection conditions matched when comparing sections (datasheet A03098-1; standard IHC practice). If staining changes, confirm the biological interpretation with an independent antibody or orthogonal assay rather than attributing it directly to phosphorylation (standard antibody-validation practice).
How can I use IF to investigate an ambiguous PREX1 IHC pattern?
Use IF as a separate validation experiment and multiplex PREX1 with a marker for the cell population being assessed, such as an immune-cell or neuronal-cell marker selected for that specimen (HPA: tissue profile; standard IF practice). Choose spectrally separated fluorophores and check unstained tissue for autofluorescence before assigning puncta or weak signal (standard IF practice). Because PREX1 is mainly cytosolic and lacks a transmembrane segment, optimise permeabilisation for access to the intracellular epitope; the antibody’s precise epitope is not supplied (UniProt Q8TCU6: subcellular location, topology; evidence scope: epitope not supplied). The atlas reports vesicular and cytosolic IF localisation, which can guide comparison with chromogenic patterns (HPA: subcellular profile). Include single-stain and secondary-only controls for channel assignment (standard IF practice).
How do I distinguish nonspecific brown staining from PREX1 signal?
Compare the stained section with a no-primary control and inspect pigment, tissue edges, damaged areas, and diffuse extracellular deposits (standard IHC practice). Block endogenous peroxidase before chromogenic detection and check the secondary detection system for nonspecific binding (standard IHC practice). The catalog brain-section example used 3% BSA for 0.5 hour and a primary dilution of 1:25; those conditions are a starting reference for this antibody, not proof they suit every tissue (datasheet A03098-1). The tissue atlas rates PREX1 staining as Supported but notes presumed off-target binding that was disregarded (HPA: reliability description). Prioritise signal in plausible cells and compartments over uniformly stronger staining (HPA: tissue profile; UniProt Q8TCU6: subcellular location; standard IHC practice).
What should I measure when PREX1 staining varies across tissue compartments? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and scoring region before examining group labels, then score cytoplasmic intensity and the percentage of positive cells within that population (standard IHC quantification practice; HPA: tissue profile). An H-score combines intensity categories with their percentages; report the categories and threshold used so results are reproducible (standard IHC quantification practice). For infiltrating cells, positive-cell density per mm² can complement percentage positivity when cell abundance differs between sections (standard IHC quantification practice). Normalise to eligible cells or analysable tissue area, and exclude folds, edges, and necrotic regions using the same rules throughout (standard IHC quantification practice). Report membrane-associated staining separately if it is a study endpoint (UniProt Q8TCU6: subcellular location; standard IHC quantification practice).
Which PREX1 staining findings warrant a specificity check?
A plausible positive is cytoplasmic, sometimes membrane-associated, staining in an appropriate cell population; the atlas reports high staining in lung macrophages and cerebellar Bergmann glia (UniProt Q8TCU6: subcellular location; HPA: tissue profile). Nuclear-only signal or staining concentrated in cells reported as undetected, such as adipocytes, warrants closer review rather than immediate biological interpretation (UniProt Q8TCU6: subcellular location; HPA: adipocytes not detected). Compare suspicious areas with section morphology, a no-primary control, and an independently stained positive section (standard IHC practice). Edge effects, necrotic deposits, and endogenous peroxidase can mimic chromogenic signal (standard IHC practice). Because the atlas notes presumed off-target binding, confirm unexpected patterns with an independent antibody or orthogonal evidence (HPA: reliability description; standard antibody-validation practice).
Boster reagents
Best PREX1 / Phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 1 protein IHC Antibodies
A03098-1 has real IHC-P images from human brain paraffin sections (catalog image captions). No IF/ICC data are supplied (catalog).
Real IHC data
Anti-PREX1 Antibody (C-term)
Cat # A03098-1
A03098-1 is listed for human IHC-P (catalog applications and reactivity). Its IHC images show PREX1 staining in paraffin-embedded human brain sections, with paraformaldehyde fixation in one caption and formalin fixation in another (catalog image captions).
Which to pick: For human tissue IHC-P, choose A03098-1: this rabbit polyclonal antibody has a listed dilution of 1:10–1:50 (catalog), and its own images document human brain paraffin sections (catalog image captions). For IF/ICC, A03098-1 has no listed application, dilution, or image (catalog). For other species, A03098-1 has documented reactivity only with human samples (catalog).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q8TCU6 (PREX1_HUMAN, Phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 1 protein).
- Human Protein Atlas. PREX1 tissue IHC expression (reliability: Supported).
- Human Protein Atlas. PREX1 subcellular location (ICC-IF): Localized to vesicles and cytosol..
- Human Protein Atlas. PREX1 antibody validation summary (1 antibodies).
- PREX1 integrates G protein-coupled receptor and phosphoinositide 3-kinase signaling to promote glioblastoma invasion. Oncotarget 2017 — PMC5352422.
- Phosphatidylinositol-3,4,5-Trisphosphate Dependent Rac Exchange Factor 1 (PREX1) is a Novel Predictor of Prognosis for Breast Cancer Patients: A Retrospective Case Series. Medical science monitor : international medical journal of experimental and clinical research 2019 — PMC6738004.
- Genome-wide enhancer-gene regulatory maps link causal variants to target genes underlying human cancer risk. Nature communications 2023 — PMC10520073.
- ERK/MAPK Signaling Drives Overexpression of the Rac-GEF, PREX1, in BRAF- and NRAS-Mutant Melanoma. Molecular cancer research : MCR 2016 — PMC5065759.
- PubMed PMID:11955434 — UniProt-cited evidence.
- PubMed PMID:11230166 — UniProt-cited evidence.
- PubMed PMID:11780052 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for PREX1 (Phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 1 protein). Expected localisation Cytoplasmic staining; membrane staining in Bergmann glia (HPA tissue IHC). Antigen retrieval: Citrate pH 6 HIER, heat-mediated (datasheet A03098-1). Validated IHC antibody: A03098-1 at 1:10-1:50 (the product's own IHC validation image is shown). Controls (HPA): positive Cerebellum (Bergmann glia - cytoplasm/membrane); negative Adipose tissue. IHC-P workflow on paraffin sections. Protocol steps: 1. Sample: Formaldehyde-fixed, paraffin-embedded human brain tissue (datasheet A03098-1); 2. Fixation: Image formalin-fixed; duration unreported (datasheet A03098-1); 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 A03098-1); 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: Rabbit anti-PREX1, 1:10-1:50 (datasheet A03098-1); 9. Primary incubation: 1 hours at 37°C (datasheet A03098-1). Watch for: Fixation: Formalin-fixed paraffin sections were used (selected-SKU IHC image A03098-1); keep fixation consistent (standard IHC practice; not target-specific); Caveat: Presumed off-target binding may mimic PREX1 staining (HPA tissue IHC); Isoform / epitope: 3 isoforms; epitope conservation is unknown (UniProt); Regulation: Expression is highest in leukocytes and brain (UniProt). Evidence: UniProt Q8TCU6, HPA tissue IHC · Supported, HPA ICC-IF · vesicles and cytosol., Datasheet A03098-1, PMC5352422, PMC5065759. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/PREX1/immunohistochemistry-ihc-guide.