Figure 1.
ADP activates ASK1/MKK4/JNK1/2 in an H2O2-dependent manner. NR8383 cells were pre-incubated ± catalase (100 U/ml) for 15 min before stimulation with 400 µM ADP for the indicated times. Whole cell lysates (A–D) or ASK1 immunoprecipitates (E) were analyzed by Western blotting. ADP induced the increase in phosphorylation of JNK1/2 (A), c-Jun (B), MKK4 (C) and ASK1 (E) that was abrogated by exogenous catalase. ADP did not stimulate the phosphorylation of MKK7 (D) but TNF-α did, as previously reported. Shown are representative blots and bar graphs (B–E) represent the mean and standard deviation of photon counts obtained as described in Methods; n = 3, *p < 0.05, **p < 0.01.
