Effect of caspase inhibitors on proteolytic cleavage of PKC in primary cortical cells treated with glutamate. Primary cortical cells were cultured for 7 days and then treated with 1 mM glutamate with or without 30 minutes of pre-treatment with 100 μM caspase-3 specific inhibitor z-DEVD or a pan-caspase inhibitor z-VAD. After 6 h cells were harvested and total protein was extracted from the cytosol and cell lysates. PKC and its fragments were assessed by Western blot analysis as described under "Methods". Immunoblots indicate the presence of PKC (80 kDa) and its 48 kDa and 45 kDa breakdown products (BDPs). Note that glutamate treatment results in the formation of greater amounts of the 2 BDPs (lanes 2 and 4) in the cytosol and cell lysates compared to the untreated controls (lanes 1 and 3). Pre-treatment of cortical cells with 100 μM z-DEVD or z-VAD prior to glutamate inhibits the formation of PKC to its BDPs to levels seen in untreated control cells (lanes 7,8).