Figure 5.

Cooperative roles of CDK and DDK in cell cycle progression from G1 to G2 phase. CDK and DDK promote G1-S phase transition and are required for proper S phase progression (arrows). In addition, these two kinases act in concert during G2 phase. CDK is required for prevention of chromosomal DNA re-replication, whereas DDK is essential to repress untimely histone gene expression, thereby helping ensure centromere integrity.