Retinoblastoma-E2F pathway (RB-E2F) (RB-E2F)

The Retinoblastoma-E2F (RB-E2F) pathway is a fundamental regulatory axis that governs the G1 to S phase transition in the mammalian cell cycle (Giacinti & Giordano, 2006). In normal cells, the Retinoblastoma protein (RB) acts as a molecular brake by binding to E2F transcription factors, thereby preventing the transcription of genes essential for DNA synthesis. This brake is released when RB is phosphorylated by Cyclin-dependent kinases 4 and 6 (CDK4/6), a process triggered by mitogenic signaling (O'Leary et al., 2016). In the majority of human cancers, this pathway is deregulated—often through RB1 loss, p16INK4a inactivation, or Cyclin D1 amplification—leading to persistent E2F activity and autonomous cell division. Therapeutic approaches targeting this deregulation include CDK4/6 inhibitors like palbociclib, which aim to restore RB's inhibitory function, and oncolytic viruses like tasadenoturev, which are designed to replicate specifically in cells with a dysfunctional RB-E2F axis (Fueyo et al., 2003).

Other names

RB-E2F axispRb-E2F pathwayCyclin D-CDK4/6-RB pathwayRB1-E2F signaling axis

Inhibition of CDK4/6 to prevent Retinoblastoma protein (RB) phosphorylation, thereby maintaining RB-mediated repression of E2F transcription factors; selective viral replication in cells with a dysfunctional RB-E2F axis.