The retinoblastoma (Rb) protein regulates progression into S phase by regulating ___________ activity.

Question

Quizplus · Accepted Answer

The retinoblastoma protein regulates progression into S phase by regulating E2F activity. When Rb is bound to E2F, it prevents E2F from activating the transcription of genes required for S phase entry. Only when Rb is phosphorylated by CDK4/6 and cyclin D can it release E2F and allow for progression into S phase. P53 is a tumor suppressor protein that plays a role in cell cycle arrest and apoptosis in response to DNA damage, but it is not directly involved in regulating S phase entry. CDC28 is a yeast CDK and not relevant to mammalian cell cycle regulation.

The Retinoblastoma (Rb) Protein Regulates Progression into S Phase by Regulating