PKCδ mediates dieldrin-induced DNA fragmentation and nuclear condensation in N27 cells. N27 cells were pretreated with 1–3 μM rottlerin for 30 min, and then treated with 100 μM dieldrin for another 3 hr. In A, DNA fragmentation was quantitatively measured by ELISA DNA fragmentation assay kit. Each bar represents mean ± SEM for two separate experiments in triplicate. **p < 0.01 compared with dieldrin-treated group. In B, chromatin condensation was observed using Hoechst 33342 staining. The percentage of nuclear condensation was calculated by counting positive cells in three to five randomly selected regions. The experiment was repeated three times, and similar results were obtained.