sentences:  Binding of Cdc45 to chromatin depends on Clb-Cdc28 kinase activity as well as functional Cdc6 and Mcm2, which suggests that Cdc45 associates with the pre-RC after activation of S-phase cyclin-dependent kinases (CDKs).As indicated by the timing and the CDK dependence, binding of Cdc45 to chromatin is crucial for commitment to initiation of DNA replication.During S phase, Cdc45 physically interacts with Mcm proteins on chromatin; however, dissociation of Cdc45 from chromatin is slower than that of the Mcm, which indicates that the proteins are released by different mechanisms.