Effect of caspase inhibitors on rECP-induced apoptosis. (A) To investigate the apoptotic pathway, BEAS-2B cells were pretreated with 20 μM general caspase inhibitor (Z-VAD), respectively, for 30 min before rECP treatment. (B and C) Cells were treated with 20 μM caspase 9 or 12 inhibitor, Z-LE(OMe)HD(OMe)-FMK (Z-LEHD) or Z-ATAD-FMK (Z-ATAD), respectively, for 30 min before rECP treatment. After 48 h incubation in the presence or absence of 20 μM rECP, total cell lysates were resolved by 10% SDS-PAGE, and relative cleaved PARP was determined by western blotting with anti-PARP and anti-actin followed by quantitative analysis. All data represent the arithmetic mean ± SEM. ***P < 0.001.