The entry of a cell into mitosis is regulated by an elaborate network of kinases and phosphatases, that controls both the timing of the division, and the complete reorganization of the cellular architecture. Cyclin/Cdk1(CDC2) is thought to be the major kinase that initiates the onset of mitosis. The checkpoint kinases CHEK1 and CHEK2, when activated by ATM, mediated the CycB-CDC2 complex activity by inhibiting its direct activator CDC25C. The transcription factor FoxM1, peaking in the late G2 phase, directly enhance cyclin B transcription. Transcription factors and protein modifiers regulates the amount of the components of the large multiprotein complexes involved in the mitosis progression (cohesin, centromer-kynetochore and the mitotic spindle), their recruitment and the activity of these complexes.
