The regulation of the G1 checkpoint is a complex process involving multiple signaling pathways. Key steps include:
The accumulation of cyclins D and E, which bind to and activate their respective CDKs. The phosphorylation of Rb, leading to the release of E2F transcription factors that promote the expression of genes required for DNA synthesis. The activation of the p53 pathway in response to DNA damage, which can halt the cell cycle and initiate repair mechanisms.
