It has been reported previously that cyclin G1 enables cells to overcome radiation-induced G
2 arrest and increased cell death and that these effects are mediated by transcriptional
activation of cyclin B1. In this study, we further investigated the mechanism by which cyclin
G1 transcriptionally activates cyclin B1. Deletion or point mutations within the cyclin B1
promoter region revealed that the c-Myc binding site (E-box) is necessary for cyclin G1-
mediated transcriptional activation of cyclin B1 to occur. In addition, the kinase activity of …