FIG. 4.

Role of mitochondrial oxidants in the activation of JNK1. (A) Inhibitory effect of the peroxide-scavenging agent NAC on JNK1 activity. Where indicated, cells were incubated with NAC for 15 h prior to pyruvate stimulation. (B) Effects of increasing amounts of GSTpi expression on pyruvate-stimulated JNK1 activity. (C) Corresponding level of GSTpi protein expression in total cellular lysate in control transfected (−) or GSTpi-transfected (2 μg) cells. The amount of GSTpi in transfected cells is underestimated in this blot since transfection efficiency was approximately 20%. (D) Exogenous catalase blocks pyruvate-induced JNK1 activation. (E) Levels of DHR123 fluorescence 15 min after treatment with various mitochondrial respiratory inhibitors and (F) the corresponding levels of JNK1 activity.