FIG. 6.

Impaired JNK1 activation in RIP^−/− and TRAF2^−/− MEF cells is associated with their resistance to H₂O₂-induced cell death. (A) JNK1, but not JNK2 and p38, is involved in H₂O₂-induced cell death. wt MEF cells, JNK1^−/−, JNK2^−/−, and p38^−/− primary fibroblasts were treated with H₂O₂ (500 μM) for 12 h. Cell death was quantified by the determination of LDH leakage. Data are presented as means ± standard deviations from at least three independent experiments. (B) H₂O₂-induced JNK activation in wt MEF cells. Cells were treated with H₂O₂ (500 μM) for up to 2 h. GST, glutathione S-transferase. (C) JNK activation in RIP^−/−, TRAF2^−/−, and FADD^−/− cells upon H₂O₂ treatment (500 μM, 30 min). (D) JNK activation in TNFR1^−/− cells upon H₂O₂ treatment (500 μM, 30 min). JNK kinase activity was determined using glutathione S-transferase-c-Jun as the substrate, as described in Materials and Methods. IgG, immunoglobulin G; IP, immunoprecipitation.