Curcumin-generated ROS activates Chk1 and Chk2 kinases. Curcumin-generated ROS activates Chk1 and Chk2 kinases. A, lysates were prepared from HCT116+ch3 (H3) that were either mock treated or exposed to 30 μmol/L curcumin in the presence or absence of 5 mmol/L NAC or 1 mmol/L glutathione (GSH). Lysates were then subjected to immunoblotting with phospho-specific Chk1 (S317) and Chk2 (T68) as well as total Chk1, Chk2, and tubulin antibodies. B, mock-treated and curcumin-treated (30 μmol/L) H3 cells were incubated in the presence or absence of 5 mmol/L NAC as indicated. Cells were subsequently harvested, stained with PI, and analyzed by flow cytometry. Columns, mean percentage of G2-M cells measured in three independent experiments; bars, SD. *, P < 0.01. Zhihua Jiang et al. Mol Cancer Ther 2010;9:558-568 ©2010 by American Association for Cancer Research