The MCM2-7 complex, which may act as a replicative helicase during DNA 
synthesis, plays a central role in S-phase genome stability. MCM proteins are 
required for processive DNA replication and are a target of S-phase checkpoints. 
Loss of MCM function causes DNA damage and genome instability. MCM expression is 
upregulated in proliferating cells, providing a diagnostic marker for both 
cancerous cells and cells with the potential to become malignant. The role of 
the MCM complex in genome integrity reflects its activity both at active 
replication forks and away from forks.