(A) IC50 values (in μM) of 1, 2, etoposide, and cisplatin against A549 cells in the absence and presence of apoptosis inhibitor, z-VAD-FMK (5 μM) after 72 h incubation. (B) IC50 values (in μM) of 1 and 2 against A549 cells in the absence and presence of H2O2-induced necrosis inhibitor, IM-54 (10 μM), and necroptosis inhibitor, necrostatin-1 (60 μM) after 72 h incubation. Student’s t-test, p < 0.05 or 0.01. Error bars represent standard deviations.