What happens when rb is phosphorylated?

When retinoblastoma protein (Rb) is phosphorylated, it undergoes a conformational change that inactivates its ability to bind to E2F transcription factors. This release of E2F allows for the transcription of genes necessary for cell cycle progression, particularly the transition from the G1 phase to the S phase. As a result, the cell is enabled to proliferate and divide. Phosphorylation of Rb is a crucial regulatory step in the cell cycle, particularly in response to growth signals.