PathwayStep4557 PathwayStep4556 Activation of Cyclin B/Cdk1 by Cdc25a (string) protein Association of Cyclin B/Cdk1 with replicative origin inhibits pre-RC formation E2F-enabled inhibition of pre-replication complex formation Authored: Gopinathrao, G, 2004-05-26 17:05:00 Pubmed11090133 Pubmed11231579 Reactome Database ID Release 43113507 Reactome, http://www.reactome.org ReactomeREACT_1321 Under specific conditions, Cyclin B, a mitotic cyclin, can inhibit the functions of pre-replicative complex. E2F1 activates Cdc25A protein which regulates Cyclin B in a positive manner. Cyclin B/Cdk1 function is restored which leads to the disruption of pre-replicative complex. This phenomenon has been demonstrated by Bosco et al (2001) in Drosophila.