Effect of caspase-3 inhibitor on dieldrin induced PKCδ proteolytic cleavage. In A, N27 cells were pretreated with caspase-3 specific inhibitor, Z-DEVD-FMK (50 μM), for 30 min, and then exposed to 100 μM dieldrin for another 3 hr and cytosolic proteins were collected as described in "Materials and Methods." PKCδ was detected by Western blot, and equal protein loading was confirmed by reprobing with β-actin (43 kDa). Veh represents 0.2% DMSO. In B, Densitometric data of cleaved (41 kDa) and full-length (72 kDa) PKCδ bands in A. Densitometric analysis was performed to determine the level of inhibition of proteolytic cleavage of PKCδ by caspase-3 inhibitor. Density of each band was normalized to 43 kDa β-actin band prior to analysis. The data are expressed as a ratio of cleaved versus full-length. **p < 0.01 compared with vehicle-treated group and ##p < 0.01 compared with dieldrin-treated group.