Cell cycle progression mechanisms: slower cyclin-D/CDK4 activation and faster cyclin-E/CDK2.

Our work provides an unprecedented mechanistic understanding of the distinct activation scenarios of cyclin-D/CDK4 and cyclin-E/CDK2 in cell cycle regulation, underpinning the slower activation of cyclin-D/CDK4 in the more extended G1 phase and the rapid activation of cyclin-E/CDK2 in the brief G1/S transition. Our findings address a long-standing question in cell cycle biology and suggest the design of targeted CDK4 inhibitors.