The cell cycle is divided into phases: G1, S, G2, and M. Different cyclins and CDKs are responsible for transitioning the cell through these phases. For instance, Cyclin D pairs with CDK4/6 to progress through the G1 phase, while Cyclin E/CDK2 pushes the cell from G1 into the S phase. Cyclin A/CDK2 and Cyclin B/CDK1 are active in the S and G2/M phases, respectively. The precise control of these stages is crucial for normal cell proliferation.
