Activation of PTP is required for FLLL12-induced expression of DR5 and apoptosis. (A–E) A549 cells were pretreated with phosphatase inhibitor cocktail (PIC, supplied solution was diluted with culture media as shown in the figure) (A, B), sodium orthovanadate (SOV) (C, D) and alkaline phosphatase inhibitor imidazole (IM) (E, F) for 2 h followed by treatment with FLLL12 for 24 h. Apoptosis was quantified by Annexin V-PE staining and expression of DR5, cleaved caspase-3 and cleaved PARP were analyzed by Western blotting.