tokens: The cyclins bind to and activate the CDK , which leads to phosphorylation ( and then inhibition ) of the tumor suppressor protein , pRb . pRb controls commitment to progress from the G1 to S phase , at least in part by repressing the activity of the E2F transcription factors known to promote cell proliferation .
folded_tokens: the cyclin bind to and activate the cdk , which lead to phosphorylation ( and then inhibition ) of the tumor suppressor protein , prb . prb control commitment to progress from the g1 to s phase , at least in part by repress the activity of the e2f transcription factor know to promote cell proliferation .