Cyclin-dependent kinase 6 (CDK6) is a 40 kDa member of the CDK family of mitotic kinases involved in cell cycle progression. CDKs are the catalytic subunits of the cyclin/CDK complexes, which phosphorylate substrates on threonine/serine residues. CDK6 associates with the D-type cyclins and is important in the progression of cells from the G1-phase to the S-phase of the cell cycle. Loss of normal cell cycle regulation is the hallmark of human cancers, and alteration of the components involved in cell cycle regulation occurs in most human tumors. This suggests that CDK6 is an attractive target for the development of pharmacological agents for the treatment of cancer. Recently, several studies have indicated a novel role for cdk6 in differentiation, also. Probably involved in the control of the cell cycle. Interacts with D-type G1 cyclins.