# PIK3R1

Source: https://onco.cc/targets/pik3r1/  
OnCo record `pik3r1` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

PIK3R1 (Phosphatidylinositol 3-kinase regulatory subunit alpha) is a gene whose normal job is to hold cell growth in check. 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 Endometrial cancer, Colorectal cancer, Breast cancer and 5 more.

## Summary

Binds to activated (phosphorylated) protein-Tyr kinases, through its SH2 domain, and acts as an adapter, mediating the association of the p110 catalytic unit to the plasma membrane. Necessary for the insulin-stimulated increase in glucose uptake and glycogen synthesis in insulin-sensitive tissues. Plays an important role in signalling in response to FGFR1, FGFR2, FGFR3, FGFR4, KITLG/SCF, KIT, PDGFRA and PDGFRB.

CIViC holds 4 clinical evidence items and 0 assertions across 2 variants, naming Doxorubicin, Buparlisib, MTOR Kinase Inhibitor PP242 and Aspirin. Open Targets scores its association with cancer at 0.87 (direct and indirect evidence; datatypes clinical 0.67, affected pathway 0.85, literature 0.98, genetic association 0.71, somatic mutation 0.91). IntOGen calls it a driver in 24 cohorts (9 activating, 14 loss-of-function), covering Adenoid Cystic Carcinoma, Invasive Breast Carcinoma, Cholangiocarcinoma, Colon Adenocarcinoma, Colorectal Adenocarcinoma, Glioblastoma and others.

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: phosphoinositide-3-kinase regulatory subunit 1; Phosphatidylinositol 3-kinase regulatory subunit alpha; GRB1; p85-ALPHA; p85; p85alpha
- Tags: cancer-genes-wave
- Symbol: PIK3R1
- Class: tumor-suppressor
- Biology: Binds to activated (phosphorylated) protein-Tyr kinases, through its SH2 domain, and acts as an adapter, mediating the association of the p110 catalytic unit to the plasma membrane. Necessary for the insulin-stimulated increase in glucose uptake and glycogen synthesis in insulin-sensitive tissues. Plays an important role in signalling in response to FGFR1, FGFR2, FGFR3, FGFR4, KITLG/SCF, KIT, PDGFRA and PDGFRB. Likewise, plays a role in ITGB2 signalling. Modulates the cellular response to ER stress by promoting nuclear translocation of XBP1 isoform 2 in a ER stress- and/or insulin-dependent manner during metabolic overloading in the liver and hence plays a role in glucose tolerance improvement. Location: Cytoplasm (UniProt). Locus 5q13.1 (HGNC).
- Where found: Endometrial cancer: Open Targets association 0.71 with endometrial cancer (MONDO_0011962); IntOGen driver in 4 cohorts (UCEC); Colorectal cancer: Open Targets association 0.68 with colorectal cancer (MONDO_0005575); CIViC evidence names this disease; Breast cancer: Open Targets association 0.60 with breast cancer (MONDO_0007254); CIViC evidence names this disease; Skin cancer: Open Targets association 0.63 with skin cancer (MONDO_0002898); Sarcomas: CIViC evidence names this disease; Gastric & gastro-oesophageal junction cancer: IntOGen driver in 2 cohorts (STAD)

## 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: Open Targets known-drug datatype score 0.67; IntOGen calls it an activating (Act) driver in 9 cohorts; IntOGen calls it a loss-of-function (LoF) driver in 14 cohorts; CIViC holds 4 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.
- Diseases the sources name that have no OnCo cancer page yet, so they are not linked: Low-Grade Glioma, NOS.

## Sources

- HGNC HGNC:8979: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:8979
- UniProt P27986: https://www.uniprot.org/uniprotkb/P27986/entry
- NCBI Gene 5295: https://www.ncbi.nlm.nih.gov/gene/5295
- Ensembl ENSG00000145675: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000145675

## 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: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Endometrial cancer](https://onco.cc/cancers/endometrial/), [Gastric & gastro-oesophageal junction cancer](https://onco.cc/cancers/gastric/), [Leukaemia (all types)](https://onco.cc/cancers/leukaemia/), [Ovarian cancer](https://onco.cc/cancers/ovarian/), [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/), [Skin cancer (all types)](https://onco.cc/cancers/skin-cancer/)

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JSON: https://onco.cc/api/v1/entities/pik3r1.json