<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>S-phase onset is controlled, so that it occurs only once every cell cycle. DNA is licensed for replication after mitosis in G(1), and passage through S-phase removes the license to replicate. Licensing factors are required for licensing and central to ensuring that replication occurs once per cell cycle. (from J Biol Chem 2001 Nov 30;276(48):44905-11)</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>