(A) Effect of THC and the pan-caspase inhibitor ZVAD (10 μM) on the viability of Atg5+/+ and Atg5–/– MEFs (36 h; percentage of viable cells relative to the corresponding Atg5+/+ vehicle-treated cells, mean ± SD; n = 3). (B) Effect of THC on the apoptosis of Bax/Bak WT and Bax/Bak DKO MEFs as determined by cytofluorometric analysis of Annexin V/propidium iodide (PI) (24 h; mean ± SD; n = 3). The mean ± SD percentage of Annexin V–positive/PI-positive and Annexin V–positive, PI-negative cells is shown in the upper and lower corners, respectively. (C) Effect of THC on eIF2α phosphorylation (3 h; n = 3) and LC3 lipidation (18 h; n = 4) of Bax/Bak WT and DKO MEFs. (D) Left: Effect of THC on autophagy and apoptosis of U87MG cells transfected with siC or siATG1. Green bars, cells with LC3 dots; red bars, active caspase-3–positive cells; white bars, cells with both LC3 dots and active caspase-3 staining. Data correspond to the percentage of cells with LC3 dots (green bars), active caspase-3–positive cells (red bars), and cells with LC3 dots and active caspse-3 staining (white bars) relative to the total number of transfected cells at each time point (mean ± SD; n = 3). Right: Representative photomicrographs (36 h; scale bar: 20 μm). (E and F) Effect of THC on apoptosis (E; 24 h; n = 3) and loss of mitochondrial membrane potential as determined by DiOC 6 (3) staining (F; 24 h; n = 4) of Atg5+/+ and Atg5–/– MEFs. In E, the mean ± SD percentage of Annexin V–positive/PI-positive and Annexin V–positive, PI-negative cells is shown in the upper and lower corners, respectively. **P < 0.01 compared with THC-treated Atg5+/+ (A, E, and F) and Bax/Bak WT (B) MEFs and from THC-treated, siC-transfected cells (D).