Interrelationships between the apoptotic and oncotic signaling cascades of cell death in PV. The abilities of caspase and calpain inhibitors and the chelator of intracellular free calcium, BAPTA/AM, to diminish the pathobiological effects of 1 mg/ml PVIgG-1b or PVIgG-2b in keratinocyte monolayers were tested using functional assays described in Materials and Methods. A and B: *, significant (P < 0.05) differences from control, non-treated monolayers; #, statistical significance (P < 0.05) compared with the results obtained with PVIgG alone. C: *, significant differences from values with PVIgG-1b or IVIgG-2b given alone. A: Effects of a mixture of calpain inhibitors MDL-28170 (10 μmol/L), PD-150606 (50 μmol/L), and CSP (50 μmol/L) on the enzymatic activity of caspase 3 in keratinocyte monolayers after 24 hours of incubation. B: Effects of a mixture of caspase inhibitors DEVD-CHO (10 μmol/L), Z-DEVD-FMK (10 μmol/L), and Z-DCB-MK (100 μmol/L) on the enzymatic activity of calpain in keratinocyte monolayers after 24 hours of incubation. C: Effects of 10 μmol/L BAPTA/AM on the abilities of PVIgG-1b or PVIgG-2b 1) to induce acantholysis; 2) to promote TUNEL positivity and 3) TBD positivity; and 4) to elevate caspase 3 and 5) calpain activities in keratinocyte monolayers after 24 hours (TUNEL, TBD, and enzymatic activities) and 48 hours (acantholysis) of incubation.