Figure 4

p53 inhibits DNA replication mediated by E2. (A) A transient HPV replication assay performed in U2OS cells co-transfected with a plasmid containing the HPV 16 origin of replication (pOri) and plasmids expressing HPV 16 E1 and the HPV 16 E2 protein (top panel) or HPV 16 E1 and the HPV 16 E2m1 protein (bottom panel) in the combinations and amounts shown. After 72 hours DNA was extracted from the cells and digested with XmnI to linearise pOri and either DpnI to remove unreplicated (input) DNA or MboI to remove replicated DNA. Linearised pOri was then detected by Southern analysis using a specific probe. The resulting autoradiograph is representative of several experiments. (B) A transient replication assay was performed exactly as described above but it this case pOri was co-transfected into U2OS cells with plasmids expressing wild type or mutated E2 proteins in the absence or presence of a plasmid expressing p53. The data shown is representative of several experiments.