Proteolytic cleavage of PKCδ following dieldrin treatment in N27 cells. In A, N27 cells (~1 × 107 cells) were exposed to 100 μM or 300 μM dieldrin for 3 hr at 37°C, and cytosolic proteins were collected as described in "Materials and Methods." Approximately 5 μg of cytosolic proteins were resolved on 10% SDS-polyacrylamide gel, revealing native PKCδ (72 kDa), the catalytic subunit (41 kDa) and the regulatory subunit (38 kDa) of proteolytically cleaved PKCδ. In B, rat brain slices were exposed to 30 μM dieldrin for 3 hr. PKCδ was detected by Western blot and equal protein loading was confirmed by reprobing with β-actin (43 kDa). Veh represents 0.2% DMSO.