DNA replication in eukaryotic cells is dependent on the phosphorylation of the pre-replicative complex (preRC) at the origin of replication. Two complexes of proteins mediate this event, the cyclin dependent kinase (CDK) complex, and the Cdc7 kinase-ASK complex. The activity of Cdc7 kinase oscillates during cell cycle. The major targets of Cdc7 kinase are proteins that belong to the MCM complex (mini chromosome maintenance proteins). Cdc7 kinase was also found to be important in meiosis, check