List three specific checkpoints that the cell monitors before proceeding through the cell cycle and describe in detail the checkpoint mediated by p53 (including what thecheckpoint looks for and when it occurs; what intracellularproteins are involved; how does p53 interact with cyclins and CDKs). For one of the three checkpoints, describe what could happen if the cell cycle proceeds past a checkpoint even though it should have stopped.

List three specific checkpoints that the cell monitors before proceeding through the cell cycle and describe in detail the checkpoint mediated by p53 (including what the checkpoint looks for and when it occurs; what intracellular proteins are involved; how does p53 interact with cyclins and CDKs). For one of the three checkpoints, describe what could happen if the cell cycle proceeds past a checkpoint even though it should have stopped.