Retinoblastoma protein (RB) - E2F transcription factor 1 (E2F1) pathway (RB/E2F1 pathway)

The RB/E2F1 pathway is a central regulatory module of cell cycle progression and cell proliferation. The Retinoblastoma protein (RB) acts as a transcriptional corepressor by interacting with the E2F family of transcription factors (especially E2F1), forming RB-E2F complexes that bind to E2F1 sites in gene promoters and repress transcription of genes essential for DNA replication and S-phase entry. Upon phosphorylation of RB by cyclin-dependent kinases (CDKs), RB releases E2F1, which then activates these cell cycle genes. RB/E2F1 regulation also impacts metabolic pathways—such as glutathione synthesis—especially in advanced cancer settings where RB is lost, conferring metabolic adaptation and resistance to therapy. RB/E2F1 also has emerging roles in RNA processing, regulation of splicing, and gene expression stability. Dysregulation of this pathway, typically through loss/mutation of RB, leads to increased E2F1 activity and uncontrolled cell proliferation, a hallmark of many cancers.

Other names

RB/E2F pathwayRetinoblastoma/E2F axisRB-E2F signalingRetinoblastoma protein and E2F1 promoter region pathwayRB-E2F1 complex

CDK inhibitors: prevent RB phosphorylation, allowing RB to bind and repress E2F1, thereby halting cell proliferation. Restoration of RB pathway function may suppress E2F1-driven genes involved in cancer cell metabolism and proliferation. Direct modulation of E2F1 or its downstream genes (experimental).