Effect of curcumin on the activation of caspases in THP-1 cells. (A) THP-1 cells were treated with vehicle (DMSO) and 50 μM curcumin (CUR) for 3, 12 and 24 hours. The cells were stained with propidium iodide (PI) staining and fluorescent caspase-3/7 substrate. PI intensity and caspase-3/7 activity were analyzed by flow cytometry. The data are representative of 3 experiments. (B) THP-1 cells were treated with 50 μM curcumin (CUR) for 0, 3, 12, 24 and 36 hours. Total lysates of the cells were subjected to SDS-PAGE electrophoresis and blotted with the antibodies against caspase-8, caspase-9, caspase-3 and PARP1. The data are representative of 3 experiments.