Figure 4.

ROS trapping and ASK1 silencing during TNFα-induced activation of apoptotic signaling. (A) ASK1 siRNA- and non-targeted control-transfected RIE-1 cells were treated with TNFα for 15 min and cell lysates were analyzed for phosphorylation of JNK and p38 by western blotting. ASK1 silencing resulted in significant reduction in the levels of JNK and p38 activation during TNFα treatment. Equal β-actin levels indicate even loading. (B) RIE-1 cells (2 × 10⁴/well) were pretreated with PBN for 2 h prior to TNFα treatment. PBN pretreatment dramatically reduced TNFα-induced RIe-1 cell death (*p < 0.05 vs. control; †p < 0.05 vs. TNFα alone). (C) TNFα-induced activation of JNK/p38 pathway and cytochrome c expression was signifi- cantly decreased with PBN pretreatment in RIe-1 cells by western blotting.