Minichromosome maintenance protein 5 (MCM5), also known as DNA replication licensing factor MCM5, is a member of the MCM family that regulates mammalian DNA replication. This family is composed of six related subunits, called the hexameric MCM2-7 complex, that are conserved in all eukaryotes. It functions as a replicative helicase, the molecular motor that both unwinds duplex DNA and powers fork progression during DNA replication. MCM proteins are also implicated in other chromosome transactions including damage response, transcription and chromatin structure. MCMs are central players in many aspects of genome stability. The MCM5 protein is upregulated in the transition from the G0 to G1/S phase of the cell cycle and may actively participate in cell cycle regulation.There is a strong positive correlation between MCM2 or MCM5 expression levels and Ki-67 labeling index. MCM5 maybe auseful proliferation marker for skin cancer, colon cancer and is of prognostic value in colon cancer and ovarian cancer. In combination with p16INK4A expression and CDC6, MCM5 may aid in the detection of cervical dysplasia.