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RPL18 / Large ribosomal subunit protein eL18 · IHC design guide
Design Immunohistochemistry for RPL18
Plan RPL18 staining in paraffin sections around the reported ubiquitous cytoplasmic tissue pattern (HPA tissue IHC). Compare cell types within each section, keeping in mind the reported low consistency between antibody staining and RNA expression (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
RPL18 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 tissue staining (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining across many tissue cell types (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A07057-3) | |
| Positive control | Testis+4 more · see all | |
| Negative control | Adipose tissue+1 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep paraffin-section fixation consistent. (standard IHC practice; not target-specific) | |
| Caveat | Antibody staining and RNA levels show low consistency (HPA tissue IHC) | |
| Regulation | Low tissue specificity; no regulator annotated (HPA tissue IHC; UniProt) | |
| Isoform / epitope | 2 isoforms; epitope differences are unspecified (UniProt) |
Section 1
Recommended RPL18 IHC & IF Protocols
The catalog antibody’s IHC-P protocol uses EDTA retrieval (datasheet A07057-3). One published melanoma IHC protocol uses citrate retrieval (PMC12808902).
| Sample | Paraffin-embedded human liver cancer tissue; fixative not specified (datasheet A07057-3) |
| Fixation | Image fixative and duration unreported (datasheet A07057-3); 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 A07057-3); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A07057-3) |
| Primary antibody | Rabbit anti-RPL18, 2-5 μg/ml (datasheet A07057-3) |
| Primary incubation | Overnight at 4 °C (datasheet A07057-3) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A07057-3) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | RPL18-positive staining in elongated or late spermatids of testis (HPA tissue IHC: High). HPA tissue profile: Ubiquitous cytoplasmic expression. No signal in the no-primary control. |
💡Decision noteStart with EDTA pH 8.0 HIER for the catalog antibody (datasheet A07057-3); use citrate pH 6.0 to follow the published protocol (PMC12808902).
Section 2
What Is the Expected RPL18 Staining Pattern?
RPL18 is a large ribosomal subunit protein found in the cytosol and on ribosomes associated with rough endoplasmic reticulum; it has no transmembrane segment (UniProt Q07020). In paraffin-section IHC, expect mainly cytoplasmic staining across many cell types, with stronger staining in some cells (HPA: ubiquitous cytoplasmic expression). Treat intensity comparisons cautiously: the tissue IHC assessment is Approved, with low consistency between antibody staining and RNA expression (HPA: tissue IHC reliability).
| Cytoplasmic staining appears in many cell types, with particularly strong signal in elongated or late spermatids. | This fits the reported distribution: RPL18 is cytosolic and associated with rough endoplasmic reticulum ribosomes (UniProt Q07020); HPA reports ubiquitous cytoplasmic expression and High staining in elongated or late spermatids (HPA: tissue IHC). Compare signal with the local negative control before scoring intensity (standard IHC practice). |
| Glandular or epithelial cytoplasm stains at a moderate intensity in appendix, breast, bronchus, cervix, or colon. | These are reported Medium patterns in the specified cell types (HPA: tissue IHC). Moderate signal can be a valid positive result; demanding uniformly strong staining would conflict with the observed tissue range (HPA: tissue IHC). Score the relevant cells and their cytoplasmic compartment separately from any diffuse slide background (standard IHC practice). |
| The dominant signal is nuclear, sharply membranous, or extracellular, with little cytoplasmic staining. | That distribution does not fit the expected tissue IHC pattern or UniProt localisation (HPA: ubiquitous cytoplasmic expression; UniProt Q07020). Investigate staining artefact and antibody specificity before calling it RPL18. Nucleolar localisation is an uncertain additional ICC-IF observation, so it does not by itself validate dominant nuclear IHC staining (HPA: subcellular). |
| Adipocytes or chondrocytes stain strongly while expected cytoplasmic staining in the same run is weak. | HPA reports RPL18 as Not detected in adipocytes and chondrocytes in its sampled tissues (HPA: tissue IHC). Strong staining there is a reason to check cross-reactivity, endogenous detection activity, and cell identification (standard IHC practice). These observations are comparison points, not proof that every such cell must always be negative. |
| Color covers tissue broadly, including spaces between cells, or a known-positive sample has no discernible signal. | Diffuse color without a cellular pattern suggests background; absence of signal in a reported positive sample leaves a negative result uninterpretable until controls pass (standard IHC practice). Use testis elongated or late spermatids as a reported High reference, or a listed Medium cell population, while allowing for HPA's low staining–RNA consistency (HPA: tissue IHC). |
💡Expected RPL18 appearanceCall an IHC result positive when staining is predominantly cytoplasmic in the relevant cells, with High signal possible in elongated or late spermatids and Medium signal reported in several glandular or epithelial populations; isolated dominant nuclear, membranous, or extracellular color is suspect (HPA: tissue IHC; UniProt Q07020).
| Cell and tissue context | HPA describes ubiquitous cytoplasmic expression but reports different levels among sampled cells, from High in elongated or late spermatids to Not detected in adipocytes and chondrocytes (HPA: tissue IHC). Interpret intensity within the identified cell population. |
| Compartment and topology | RPL18 occurs in cytosol and ribosomes associated with rough endoplasmic reticulum and has no transmembrane segment (UniProt Q07020). A predominantly cytoplasmic IHC pattern is therefore the relevant localisation check (HPA: tissue IHC). |
| Strength of tissue evidence | The listed antibody HPA046572 has Approved IHC validation, while HPA notes low consistency between antibody staining and RNA expression (HPA: antibody validation; HPA: tissue IHC reliability). Use the observed pattern as a guide, with controls for each staining run (standard IHC practice). |
| IF/ICC Q: What localisation should an image show? | A: Mainly endoplasmic reticulum and cytosol; nucleoli are an additional uncertain location (HPA: subcellular). HPA lists ICC-IF images from HEK293, MCF-7, and U2OS, and marks HPA046572 ICC as Supported (HPA: subcellular; HPA: antibody validation). |
| Situation | Likely cause | Next action |
|---|---|---|
| No cytoplasmic signal in a section containing a reported positive cell population. | The staining run may have failed, or the signal may be below the chosen detection threshold; absence alone does not establish lack of RPL18 (standard IHC practice). | Check a positive control and the negative detection control, then review antigen retrieval, antibody incubation, and detection steps using the validated IHC workflow (standard IHC practice). HPA reports High staining in elongated or late spermatids (HPA: tissue IHC). |
| Uniform brown haze obscures cell boundaries or covers areas outside cells. | Nonspecific antibody binding, excess detection signal, or residual endogenous detection activity can produce diffuse background (standard chromogenic IHC practice). | Inspect the negative detection control; review blocking, washes, antibody concentration, and detection time, then score only interpretable cellular staining (standard IHC practice). |
| Strong staining appears mainly in adipocytes or chondrocytes. | This conflicts with HPA's Not detected observations for those sampled cells and may reflect cross-reactivity or endogenous detection activity (HPA: tissue IHC; standard IHC practice). | Confirm cell identity and compare the signal with negative detection and reported positive tissue controls before assigning it to RPL18 (standard IHC practice; HPA: tissue IHC). |
| A crisp nuclear or membranous pattern dominates the section. | The dominant compartment differs from the reported cytoplasmic IHC pattern and the cytosolic, rough endoplasmic reticulum association (HPA: tissue IHC; UniProt Q07020). | Review the control slides and staining distribution; repeat with the IHC-validated antibody if the pattern persists (standard IHC practice; HPA: antibody validation). Do not treat the uncertain nucleolar ICC-IF observation as confirmation of nuclear IHC (HPA: subcellular). |
| A glandular or epithelial population stains only moderately. | Medium staining is the reported level for several sampled glandular and epithelial populations, including appendix glandular cells and bronchial respiratory epithelial cells (HPA: tissue IHC). | Assess cytoplasmic localisation and control performance before increasing signal development; moderate, well-localised staining can be the expected result (HPA: tissue IHC; standard IHC practice). |
| A negative tissue result disagrees with an RNA expression expectation. | HPA reports low consistency between antibody staining and RNA expression in its Approved tissue IHC assessment (HPA: tissue IHC reliability). | Report the observed cell type, compartment, intensity, and control results; avoid inferring protein absence from RNA alone (standard IHC practice; HPA: tissue IHC reliability). |
Experiment evidence
IHC & IF images showing RPL18 staining
A07057-3 · IHCIHC analysis of RPL18 using anti-RPL18 antibody (A07057-3). RPL18 was detected in a paraffin-embedded section of human liver cancer tissue.
A07057-3 · IHCIHC analysis of RPL18 using anti-RPL18 antibody (A07057-3). RPL18 was detected in a paraffin-embedded section of human placenta tissue. Heat
A07057-3 · IFIF analysis of RPL18 using anti-RPL18 antibody (A07057-3). RPL18 was detected in an immunocytochemical section of A549 cells. Enzyme antigen
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000063177-RPL18/tissue/cerebral+cortex#imid_14228242
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000063177-RPL18/tissue/colon#imid_14229464
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000063177-RPL18/tissue/liver#imid_14229465
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000063177-RPL18/tissue/kidney#imid_14229466
HPA · ICC-IF HEK293Human Protein Atlas immunofluorescence, HEK293, antibody HPA046572; green = RPL18, blue = nucleus, red = microtubules.
HPA · ICC-IF HEK293Human Protein Atlas immunofluorescence, HEK293, antibody HPA046572; green = RPL18, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for RPL18 IHC & IF
🧪Run testis first; elongated or late spermatids should stain (HPA: High). Use adipose tissue as the negative comparator, with adipocytes expected to show no detectable staining (HPA: Not detected); on the testis slide, treat unstained cells as a background reference, not as a validated RPL18-negative cell population (HPA: testis row identifies only elongated or late spermatids).
Positive control tissue: Testis (Elongated or late spermatids, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show RPL18 in HEK293, MCF-7, U2OS, with annotated localisation: Endoplasmic reticulum (supported), Cytosol (supported) (HPA subcellular).
Technical controls: Include a no-primary (secondary-only) control, a matched rabbit IgG isotype control, and RPL18-knockout material as a biological negative (selected A07057-3 caption: rabbit primary; standard IHC practice). Quench endogenous peroxidase and check testis sections for nonspecific DAB signal (selected A07057-3 caption: HRP/DAB detection; standard IHC practice).
⚠️Feasibility: The selected A07057-3 tissue-IHC caption does not report a fixative, and no target-specific fixation window or fixation effect is reported in the supplied evidence (selected A07057-3 caption: fixative not stated). That caption used heat-mediated EDTA retrieval at pH 8.0, but does not establish that retrieval is required (selected A07057-3 caption). Whether frozen sections or IF are easier is unreported; dense spermatid packing may complicate cell-level scoring in testis (HPA: High in elongated or late spermatids; standard histology practice).
HPA tissue IHC evidence for RPL18
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 |
|---|---|---|---|---|
| Testis | Elongated or late spermatids | 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 → |
| Cerebellum | Purkinje cells | Medium | Protein (IHC) | HPA → |
Section 3
Advanced RPL18 IHC Tips
Troubleshoot RPL18 staining in paraffin sections by checking retrieval, cytoplasmic distribution, controls, and how staining is scored.
Which retrieval conditions should I try first for RPL18 chromogenic IHC?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A07057-3). The selected antibody produced an RPL18 tissue image after this retrieval, followed by 10% goat serum block and 2 μg/ml primary antibody overnight at 4°C (datasheet A07057-3). If staining is weak, check that sections were fully deparaffinised and heated consistently before changing retrieval conditions (standard IHC practice). Compare any adjusted retrieval with the original method on adjacent sections, scoring cytoplasmic signal and tissue damage together; excessive heating can reduce interpretable morphology (standard IHC practice).
How should I assess fixation as a cause of weak RPL18 staining?
Target-specific fixation sensitivity is unknown: the selected tissue-IHC caption describes a paraffin section but does not state its fixative (datasheet A07057-3). Record the fixative, fixation interval, and processing history for each specimen, then compare sections processed alike before attributing weak staining to RPL18 abundance (standard IHC practice). Uneven preservation can change morphology and antigen accessibility across a section, so inspect the affected region and its neighbouring cells together (standard IHC practice). Keep retrieval at EDTA pH 8.0 while assessing fixation, and use the same antibody conditions across comparison sections (datasheet A07057-3; standard IHC practice).
Where should convincing RPL18 staining appear in paraffin sections?
Expect predominantly cytoplasmic staining: tissue IHC is described as ubiquitously cytoplasmic, while the protein is associated with cytosolic polysomes and rough endoplasmic reticulum ribosomes (HPA tissue IHC; UniProt Q07020 localisation). Cell imaging supports endoplasmic reticulum and cytosol localisation, with nucleolar localisation marked uncertain (HPA subcellular). Judge a strong nuclear-only chromogenic pattern cautiously, especially when adjacent cytoplasm is unstained, and inspect the matching negative control (HPA subcellular; standard IHC practice). Because RPL18 has no annotated transmembrane segment, a sharp plasma-membrane outline alone would need independent validation before assignment to RPL18 (UniProt Q07020 topology; standard IHC practice).
Could isoforms or epitope changes explain discordant RPL18 staining?
RPL18 has 2 annotated isoforms, but the supplied tissue-IHC caption does not identify which sequence the catalog antibody recognises (UniProt Q07020 isoforms; datasheet A07057-3). Check the antibody's documented immunogen or epitope against both sequences before interpreting a negative section as absence of all RPL18 (standard IHC practice; UniProt Q07020 isoforms). Phosphoserine at residue 130 and phosphothreonine at residue 158 are annotated; their effects on this antibody's staining are unknown (UniProt Q07020 modified residues). Compare a second antibody with a documented, distinct epitope on matched sections if an isoform-specific or modification-sensitive explanation matters to the study (standard IHC practice).
How can IF help resolve an ambiguous chromogenic RPL18 pattern?
Use IF as a complementary localisation check when chromogenic IHC cannot separate neighbouring cells or cytoplasmic compartments (standard IF practice). Multiplex RPL18 with a validated marker for the expected cell type in the specimen, and choose spectrally separated fluorophores after examining unstained tissue for autofluorescence (standard IF practice). Permeabilisation should allow antibody access to cytosolic and rough-endoplasmic-reticulum-associated epitopes; RPL18 has no annotated transmembrane segment (UniProt Q07020 localisation and topology; standard IF practice). Compare the IF pattern with the IHC section cautiously: cell imaging supports cytosol and endoplasmic reticulum localisation, while nucleolar localisation remains uncertain (HPA subcellular).
How do I reduce diffuse or patchy RPL18 background?
Inspect a matched section without primary antibody to separate detection-system background from antibody-dependent staining (standard IHC practice). The selected tissue-IHC image used 10% goat serum block, 2 μg/ml primary antibody overnight at 4°C, and peroxidase-based DAB detection (datasheet A07057-3). Check the routine endogenous-peroxidase block before DAB development, and examine whether pigment or damaged tissue reproduces the apparent signal in controls (standard chromogenic IHC practice). Because RPL18 staining is broadly cytoplasmic in tissue, diffuse cellular colour alone is insufficient; require preserved morphology and a clear difference from control background (HPA tissue IHC; standard IHC practice).
How should I score RPL18 across sections with different cell mixtures? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and cytoplasmic compartment before scoring, because RPL18 tissue staining is broadly cytoplasmic and levels vary among listed cell types (HPA tissue IHC). Report an H-score from intensity and percentage of positive cells, or report percentage positive with intensity separately, using identical thresholds across slides (standard IHC quantification practice). Normalise positive-cell counts or stained area to the number of eligible cells or analysed tissue area, and exclude folds, necrosis, and section edges using preset criteria (standard IHC quantification practice). Include matched controls and record batch and retrieval conditions, particularly EDTA pH 8.0, when comparing groups (datasheet A07057-3; standard IHC quantification practice).
When is an apparent RPL18-positive area likely an artefact?
A credible result follows cellular cytoplasm with preserved morphology, consistent with the reported ubiquitous cytoplasmic tissue profile and cytosolic or endoplasmic reticulum localisation (HPA tissue IHC; HPA subcellular). Question nuclear-only or membrane-outline staining without cytoplasmic signal, while treating nucleolar signal cautiously because that additional location is uncertain (HPA subcellular; UniProt Q07020 topology). Compare suspicious colour at section edges, necrotic regions, and pigment-rich areas with morphology and a no-primary control; endogenous peroxidase can also produce DAB signal (standard chromogenic IHC practice). Interpret discordance with RNA cautiously because the tissue-IHC reliability note reports low consistency between antibody staining and RNA expression (HPA tissue IHC).
Boster reagents
Best RPL18 / Large ribosomal subunit protein eL18 IHC Antibodies
Anti-RPL18 A07057-3 has real IHC images from human paraffin sections and an IF image from A549 cells (catalog image captions); listed reactivity covers human, mouse, and rat (catalog reactivity).
Real IHC data
Anti-RPL18 Antibody ®
Cat # A07057-3
A07057-3 is the sole card, with IHC images from paraffin sections of human liver cancer, placenta, rectum adenocarcinoma, and spleen (catalog IHC captions). Its IF image uses A549 cells (catalog IF caption), and its listed applications include IHC, ICC, and IF (catalog applications).
Which to pick: Choose A07057-3 for tissue IHC: its own paraffin-section captions document EDTA retrieval at pH 8.0 and 2 μg/ml primary antibody; the fixative is unreported (catalog IHC captions). For IF/ICC, the same SKU lists both applications and has an A549 IF image using 5 μg/ml primary antibody (catalog applications; catalog IF caption). For cross-species work, A07057-3 lists human, mouse, and rat reactivity, while the supplied IHC images show human tissue and the IF image shows A549 cells; clonality is unreported (catalog reactivity; catalog image captions; catalog clone field).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q07020 (RL18_HUMAN, Large ribosomal subunit protein eL18).
- Human Protein Atlas. RPL18 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. RPL18 subcellular location (ICC-IF): Mainly localized to the endoplasmic reticulum and cytosol. In addition localized to the nucleoli..
- Human Protein Atlas. RPL18 antibody validation summary (1 antibodies).
- RPL18 promotes melanoma progression and drug resistance via BTF3/STAT3-dependent mechanisms and immune modulation. iScience 2026 — PMC12808902.
- PubMed PMID:8218404 — UniProt-cited evidence.
- PubMed PMID:11875025 — UniProt-cited evidence.
- PubMed PMID:15057824 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for RPL18 (Large ribosomal subunit protein eL18). Expected localisation Cytoplasmic tissue staining (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A07057-3). Validated IHC antibody: A07057-3 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Testis (Elongated or late spermatids); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human liver cancer tissue; fixative not specified (datasheet A07057-3); 2. Fixation: Image fixative and duration unreported (datasheet A07057-3); 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 A07057-3); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A07057-3); 8. Primary antibody: Rabbit anti-RPL18, 2-5 μg/ml (datasheet A07057-3); 9. Primary incubation: Overnight at 4 °C (datasheet A07057-3). Watch for: Fixation: Keep paraffin-section fixation consistent. (standard IHC practice; not target-specific); Caveat: Antibody staining and RNA levels show low consistency (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope differences are unspecified (UniProt); Regulation: Low tissue specificity; no regulator annotated (HPA tissue IHC; UniProt). Evidence: UniProt Q07020, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the endoplasmic reticulum and cytosol. In…, Datasheet A07057-3, PMC12808902. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/RPL18/immunohistochemistry-ihc-guide.