FIGURE 3.

NGEN activates caspases‐mediated cell death. A, A549 cells were treated with or without NGEN (200 or 800 μM) for 24 hours. Extracts from untreated or NGEN‐treated cells were assayed for caspase activities using fluorogenic peptide substrates. B, A549 cells were treated with NGEN (800 μM) after pretreatment of the caspase‐3 (z‐DEVD‐fmk), caspase‐8 (z‐IETD‐fmk), and caspase‐9 (z‐LEHD‐fmk) inhibitors (100 μM) respectively for 1 hour. After 24 hours treatment, cell numbers were calculated using hemocytometers by the Trypan blue dye exclusion method. Comparisons were performed using one‐way ANOVA with Dunnett post hoc test and considered significant at the *P < .05, **P < .01, or ***P < .001 level [Color figure can be viewed at wileyonlinelibrary.com]