CDC6 and cancer: Cancer cells are also known to have deregulated replication origin activities, including licensed origin scarcity during S phase due to lack of appropriate S-phase checkpoints and/or depletion of replicative DNA helicase minichromosome maintenance complex 2-7 (MCM2-7), and unscheduled replication caused by overexpression of proteins such as chromatin licensing and DNA replication factor 1 (CDT1) and cell division cycle 6 (CDC6).