PMA treatment reverses the effect of curcumin on THP-1 cells. (A) THP-1 cells were cultured in RPMI-1640 medium with 100 ng/ml PMA for 3 days. The cells were incubated with 50 μM curcumin (CUR) for 0, 3, 6 and 12 hours. After cell lysis, otal lysates of the cells were separated and blotted with the indicated antibodies. The data are representative of 3 experiments. (B) A schematic model describing the mechanism by which curcumin can induce THP-1 apoptosis via MAPK/AP1 regulation.