CDK4 and CDK6 are Ser/Thr protein kinases that are components of protein complexes that regulate progression through the G1 phase of the cell cycle. These kinases are important integrators of mitogenic and antimitogenic signals, and are oncology drug targets. CDK4/6 inhibitors are in clinical use (e.g. abemaciclib, ribociclib and palbociclib).

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