FIG. 3.

(A) The effects of E1A, E1B, and E4orf6 on regulation of different p53-responsive constructs by p73. The p21Waf1Luc, BaxLuc, CyclinGLuc, and MDM2Luc reporter constructs were transiently transfected in Hep3B cells. Activation of the reporter constructs by CMV-p73 (0.1 μg) was measured after cotransfection of the control CMVneo vector (1.0 μg) or after cotransfection of the indicated Ad expression plasmids (1.0 μg). In the case of the MDM2Luc reporter construct, only 0.01 μg of CMV-p73 was used. Twenty-four hours posttransfection, lysates were made and the luciferase activity was measured. All transfections were performed at least two times in triplicate. The given data represent the mean values of these experiments, and the error bars indicate the variations between the independent experiments. (B) Expression of p73 in the cotransfections was verified by Western immunoblotting. (C) The effects of 12SE1A and E1A mutants [12S(Δ4–25) lacking p300 binding domain and 12S(Δ111–123) lacking pocket protein binding domain] on regulation of the BaxLuc reporter construct by p73. (D) A side-by-side comparison of the effects of the Ad proteins on the transcription activation by p53 and p73 on the various reporter constructs.