CDK4: A master regulator of the cell cycle and its role in cancer

The mammalian cell cycle is divided into four phases, Gap 1 (G1), Synthesis (S), Gap 2 (G2) and Mitosis (M), whose order and timing are critical for accurate transmission of genetic information. Consequently, a number of biochemical pathways have evolved to ensure that initiation of a particular cell cycle event is dependent on the accurate completion of another. These biochemical pathways have been termed “checkpoints.”