FIG. 2.

p53 inhibition by E1B-55-kDa abolished by E4orf3. Expression plasmids for p53 (100 ng), E1B-55-kDa (400 ng), flag-tagged E4orf3 (400 ng) and E4orf6 (100 ng), or “empty” vector constructs were cotransfected along with 1 μg of a p53 responsive luciferase reporter plasmid termed pBP100luc (30) into Saos-2 cells as indicated. At 24 h after transfection, the luciferase activity was determined. The activity of p53 alone was arbitrarily set to 100%, and the activities obtained with the different plasmid combinations were normalized accordingly.