Fig. 4

Silence of DDB2 defects the assembly of pre-replication complex. a Down regulation of DDB2 reduced the protein level of CDT1 but not SET8. HCT116 cells were treated with indicated siRNAs for 48 h, and then the cells were harvested for Western blot. The relative protein level of p21, CDT1 and SET8 were normalized and plotted on the right panel. *** Denoted P < 0.001, and the error bars indicated SD. b The mRNA level of CDT1 was insensitive to DDB2 depletion. Total RNA was extracted from cells in a, and the mRNA levels of CDT1 and DDB2 were measured by RT-qPCR. c The chromatin recruitment of MCMs was impaired once DDB2 was abolished. HCT116 cells were treated with luciferase and DDB2 siRNAs for 48 h, total cell lysate and cell fractions were blotted with indicated antibodies. The chromatin loading of MCMs was quantified and normalized to histone H3, and plotted on the right panel. ** Denoted P < 0.01, *** denoted P < 0.001