Chamaejasmenin B and neochamaejasmin C induced apoptosis. (A) Cells were treated with the compounds for 48 h and analyzed for apoptosis. The experiments were repeated three times, and error bars represent the standard deviation. bP<0.05, cP<0.01 (two-sided Student's t-test). (B) A549 cells were exposed to the compounds for 48 h, and protein extracts were immunoblotted with specific antibodies against p53, XIAP, Mcl-1, caspase-3, cleaved-caspase-3, and PARP. (C) A549 cells were pretreated with the pan-caspase inhibitor Boc-D-fmk (10 μmol/L) for 1 h and then treated with 4 μmol/L chamaejasmenin B for 48 h. The cells were analyzed for apoptosis by flow cytometry.