# SF3B1

Source: https://onco.cc/targets/sf3b1/  
OnCo record `sf3b1` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

SF3B1 (Splicing factor 3B subunit 1) is a gene that drives cell growth when it is altered. The public catalogues list it as a drug target, an oncogene driver, a tumour suppressor and a biomarker, and clinical evidence ties its variants to diagnosis, prognosis or drug response. Tied to Leukaemia, Non-Hodgkin lymphoma, Myelodysplastic syndromes / neoplasms and 5 more.

## Summary

Component of the 17S U2 SnRNP complex of the spliceosome, a large ribonucleoprotein complex that removes introns from transcribed pre-mRNAs. The 17S U2 SnRNP complex (1) directly participates in early spliceosome assembly and (2) mediates recognition of the intron branch site during pre-mRNA splicing by promoting the selection of the pre-mRNA branch-site adenosine, the nucleophile for the first step of splicing. Within the 17S U2 SnRNP complex, SF3B1 is part of the SF3B subcomplex, which is required for 'A' complex assembly formed by the stable binding of U2 snRNP to the branchpoint sequence in pre-mRNA.

CIViC holds 10 clinical evidence items and 0 assertions across 4 variants, naming Spliceostatin A, Olaparib and Etoposide. Open Targets scores its association with cancer at 0.83 (direct and indirect evidence; datatypes affected pathway 0.61, literature 0.98, genetic association 0.57, somatic mutation 0.95, animal model 0.48). IntOGen calls it a driver in 25 cohorts (24 activating, 1 loss-of-function), covering Acute Myeloid Leukaemia, Bladder Urothelial Carcinoma, Invasive Breast Carcinoma, Cholangiocarcinoma, Chronic Lymphocytic Leukaemia/Small Lymphocytic Lymphoma, Hepatocellular Carcinoma and others.

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: splicing factor 3b subunit 1; Splicing factor 3B subunit 1; SAP155; SF3b155; PRPF10; Prp10; Hsh155
- Tags: cancer-genes-wave
- Symbol: SF3B1
- Class: oncogene
- Biology: Component of the 17S U2 SnRNP complex of the spliceosome, a large ribonucleoprotein complex that removes introns from transcribed pre-mRNAs. The 17S U2 SnRNP complex (1) directly participates in early spliceosome assembly and (2) mediates recognition of the intron branch site during pre-mRNA splicing by promoting the selection of the pre-mRNA branch-site adenosine, the nucleophile for the first step of splicing. Within the 17S U2 SnRNP complex, SF3B1 is part of the SF3B subcomplex, which is required for 'A' complex assembly formed by the stable binding of U2 snRNP to the branchpoint sequence in pre-mRNA. Sequence independent binding of SF3A and SF3B subcomplexes upstream of the branch site is essential, it may anchor U2 snRNP to the pre-mRNA. May also be involved in the assembly of the 'E' complex. Also acts as a component of the minor spliceosome, which is involved in the splicing of U12-type introns in pre-mRNAs. Location: Nucleus; Nucleus speckle (UniProt). Locus 2q33.1 (HGNC).
- Where found: Leukaemia: Open Targets association 0.81 with leukaemia (MONDO_0005059); CIViC evidence names this disease; Non-Hodgkin lymphoma: Open Targets association 0.75 with non-Hodgkin lymphoma (MONDO_0018908); Myelodysplastic syndromes / neoplasms: Open Targets association 0.66 with myelodysplastic syndrome (MONDO_0018881); CIViC evidence names this disease; Breast cancer: Open Targets association 0.65 with breast cancer (MONDO_0007254); CIViC evidence names this disease; Pancreatic ductal adenocarcinoma: IntOGen driver in 2 cohorts (PAAD); Myeloproliferative neoplasms: Open Targets association 0.58 with myeloproliferative neoplasm (MONDO_0020076)

## Notes

- Written by scripts/fetch-cancer-genes.ts from CIViC, Open Targets, IntOGen, HGNC and UniProt; the function text is UniProt's, condensed and in UK spelling. Roles: CIViC lists 3 therapies; IntOGen calls it an activating (Act) driver in 24 cohorts; IntOGen calls it a loss-of-function (LoF) driver in 1 cohort; CIViC holds 10 clinical evidence items on its variants. Evidence tier "clinical-evidence" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.

## Sources

- HGNC HGNC:10768: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:10768
- UniProt O75533: https://www.uniprot.org/uniprotkb/O75533/entry
- NCBI Gene 23451: https://www.ncbi.nlm.nih.gov/gene/23451
- Ensembl ENSG00000115524: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000115524

## Connected records

- collections: [CIViC](https://onco.cc/collections/civic/), [IntOGen](https://onco.cc/collections/intogen/), [Open Targets Platform](https://onco.cc/collections/open-targets/)
- cancers: [Bladder & urothelial cancer](https://onco.cc/cancers/urothelial/), [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [Hepatocellular carcinoma](https://onco.cc/cancers/hcc/), [Leukaemia (all types)](https://onco.cc/cancers/leukaemia/), [Myelodysplastic syndromes / neoplasms (MDS)](https://onco.cc/cancers/mds/), [Myeloproliferative neoplasms (PV, ET, myelofibrosis)](https://onco.cc/cancers/myeloproliferative-neoplasms/), [Non-Hodgkin lymphoma (all types)](https://onco.cc/cancers/non-hodgkin-lymphoma/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/)
- pathways: [RNA splicing](https://onco.cc/pathways/rna-splicing/)

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JSON: https://onco.cc/api/v1/entities/sf3b1.json