The MCM4 protein (minichromosome maintenance protein 4) is a nuclear 100 kD DNA-dependent ATPase. The MCM4 protein is a component of the DNA pre-replication complex that acts to allow DNA to undergo single round of replication per cell cycle. MCM4 together with MCM6 and MCM7 have DNA helicase activity. MCM4 can be modified by phosphorylation by CDK2. Phosphorylation of MCM4 inhibits DNA replication. MCM4 has been reported to interact with the MCM6 and MCM7 (to form a 600 kD complex with helicase activity) and CDK2. The Poly6024 antibody recognizes human MCM4 and has been shown to be useful for Western blotting.