RB1

Type

Gene (protein-coding, tumor suppressor)

Description

RB1 (Retinoblastoma 1) encodes the pRb protein, a key tumor suppressor that regulates the G1/S cell cycle checkpoint. pRb is phosphorylated by CDK4/6-cyclin D complexes to release E2F transcription factors and permit cell cycle progression. RB1 loss or inactivation is a driver event in multiple cancer types. Acquired RB1 mutations are a mechanism of resistance to CDK4/6 inhibitors in breast cancer, detectable via ctDNA.

External identifiers

• HGNC: 9884
• NCBI Gene: 5925
• UniProt: P06400

Wiki sources

• wander2026-ctdna-cdk46-breast-cancer — RB1 mutations as CDK4/6 inhibitor resistance mechanism
• pcawg2020-pan-cancer-analysis — Pan-cancer driver catalog