MCM2 A gene on chromosome 3q21 that encodes one of the highly conserved mini-chromosome maintenance (MCM) proteins that are involved in initiating eukaryotic genome replication. The hexameric protein complex formed by MCM2-7 is a key component of the pre-replication complex, and may be involved in forming replication forks and in recruiting other DNA-replication-related proteins; it is required for the entry in S phase and for cell division. The sub-complex formed by MCM2, MCM4, MCM6 and MCM7 regulates the complex’s helicase activity. MCM2 is phosphorylated, and thus is regulated, by protein kinases CDC2 and CDC7. It is also the retired HUGO symbol for MCM7.