Cyclins

Cyclins are regulatory proteins that are periodically expressed and degraded along with cell cycle progression; by binding to cyclin-dependent kinases and activating their catalytic activity, they precisely drive the orderly advance of each phase of the cell cycle. They form specific complexes with CDKs that respectively regulate key checkpoints such as the G1/S transition, S-phase progression, and the G2/M transition, serving as core factors in cell proliferation control.