Fig. 4.

Curcumin induction of ROS downregulates protein phosphatase activities of PP2A and PP5. (A) Rh30 cells were treated with 0–40 μM curcumin for 24 h or (B) treated with 20 μM curcumin for 0–24 h and (C and D) Rh30 cells were pretreated with/without NAC (5 mM) for 1 h and then exposed to curcumin (0–20 μM) for 24 h, followed by western blot analysis with indicated antibodies (A, B, and D) or in vitro Ser/Thr phosphatase assay (C). Results are presented as mean ± SE (n = 6). ^aP < 0.05, difference versus control group; ^bP < 0.05, difference versus 10 μM curcumin group; ^cP < 0.05, difference versus 20 μM curcumin group.