G1 G2 M S Is DNA damaged? Is DNA replication complete? Is the mitotic spindle assembled? Are chromosomes properly segregated? adapted from: Alberts et al. Molecular Biology of the Cell, 3rd ed. G0 restriction point/START Figure 1

G1 G2 M S cyclin D cyclin E cyclin A cyclin B Cdk6 Cdk2 Cdk1 Cdk4 MPF adapted from: Alberts et al. Molecular Biology of the Cell 3rd ed. Figure 2

degraded cyclin Cdk1 OFF ON APC Cdk1 Cyclin P P Cdk1 Cyclin P Cdc25 P Wee1 P amino acids Cyclin Cdk1 IE P k1k1 k2k2 k3k3 kaka kbkb kckc kdkd keke kfkf kgkg khkh k 25 k wee Figure 3

Figure 4