What Role do Growth Signals Play in Cell Cycle Regulation?
Growth signals are crucial for the regulation of the cell cycle. They ensure that cells only divide when they are ready and when conditions are favorable. For instance, during the G1 phase, growth factors like EGF stimulate the expression of cyclin D, which forms a complex with CDK4/6. This complex phosphorylates the retinoblastoma protein (Rb), releasing E2F transcription factors that drive the cell into the S phase where DNA replication occurs.
