FIGURE 6.

MPK38 inhibits PDK1 activity toward H₂O₂-induced apoptosis and JNK-mediated transcription. A, effect of MPK38 on PDK1-mediated suppression of H₂O₂-induced apoptosis. HEK293 cells were transiently transfected with increasing amounts of wild-type and kinase-dead Mpk38 (0.4 and 0.8 μg) or Mpk38 siRNAs (100 and 200 nm) in the presence of the wild-type or mutant form (T354A) of PDK1 (1.5 μg each). Apoptotic cell death was determined in the GFP-based cell death assay. Cells exposed to 1 mm H₂O₂ for 9 h were used as a positive control. B, effect of MPK38 on PDK1-mediated suppression of JNK-mediated transcription. 293T cells were transfected with PDK1 (wild-type and mutant form (T354A), 1 μg each), Mpk38 (wild-type and kinase-dead (K40R), 0.6 and 1.2 μg), ASK1 (0.8 μg), and Mpk38 siRNAs (50 and 200 nm), together with 0.2 μg of AP-1 luciferase plasmid and β-galactosidase plasmid (0.2 μg) as an internal control in the presence or absence of c-fos (0.7 μg) as indicated. Luciferase activity was measured 48 h after transfection and normalized to β-galactosidase activity. Data represent the mean (±S.E.) of three independent experiments. RLU, relative light unit; WB, Western blot.