FIG. 1.

MdmX is unable to mediate p53 degradation. MEF 2KO (top) and H1299 (bottom) cells were cotransfected with the CMVmdm2, CMVmdmX, or CMVHPV-E6 expression vector and a CMVp53 expression vector at a 2.5:1 (MEF 2KO) or 5:1 (H1299) ratio. Each transfection contained 0.5 μg of the luciferase expression vector, pGL3Luc (Promega), and a total DNA concentration of 7 μg. Cell extracts were prepared 24 h following transfection, and equal luciferase units were analyzed via Western analysis. We have not observed any direct effect of p53 overexpression on expression of the luciferase internal control (data not shown).