FIGURE 5.

Enhancement of p53-mediated transcription by MPK38. A and B, MCF7 and p53-null HCT116 cells were transiently transfected with 0.2 μg of p53 luciferase plasmid, 0.1 μg of an expression plasmid for β-galactosidase as an internal control, and increasing amounts of wild-type and kinase-dead (K40R) forms of Mpk38 (0.5 and 1.5 μg) and Mpk38 siRNA (100 and 200 nm) as indicated in the presence of p53 or p53(S15A) (0.3 μg each). Luciferase activity was measured 48 h after transfection and normalized to β-galactosidase activity. C, MCF7 cells were transfected with 0.2 μg of p53 luciferase plasmid and increasing amounts (0.4, 0.8, and 1.2 μg) of wild-type Mpk38 or Mpkc, as indicated, in the presence or absence of p53 (0.3 μg). The expression level of p53, MPK38, and MPKC was determined by immunoblotting with the indicated antibodies. Data shown are means (± S.E.) of three independent experiments. p < 0.05 relative to control indicates significance as calculated by Student's t test. WB, Western blot.