How is cell cycle controlled?

Since any disturbance of cell cycle will lead to cell death or cancer, it is controlled and may not be disturbed (mutation, chemicals, signalling pathways) The most important check point is the G1-S transition, the other is G2-M transition, where there is replication there is cell division. The cycle is controlled by CNC (cyclin dependent proteins) with the aid of G1 cyclin and M cyclin by catalyzing interaction between subunits These cnc phosphorylate some proteins to initiate cell division (condensation...)