• RB1 controls transition from G1 to S phase of cell cycle by binding to E2F1, E2F2, or E2F3 proteins and thereby repressing promoters of genes needed for the entrance into S phase.
    • Phosphorylation performed by CDK4/cyclin D followed by CDK2/cyclin E is needed to inactivate RB1:
      • Activities of CDK4 and CDK2 protein kinases depend on the presence of their regulatory subunits, that is, cyclin D and cyclin E, respectively.
      • Regulatory activities of these subunits fluctuate in a coordinate fashion in the course of the cell cycle.
    • Loss of RB1 function upsets to unrestrained cell proliferation.
    Other topics in Molecular Targets and Pathways