ROS generation by DCQ in EMT-6 cells. A. Cells were treated with 10 μM DCQ for 30 min before measuring ROS release by the DCFH-DA assay as described in the materials and methods. B & C. EMT-6 cells were pretreated for 2 h with the strong anti-oxidants Tiron and NAC, then with DCQ (2.5, 5 and 10 μM), and later subjected to 0 Gy (-IR) or 10 Gy (+IR) radiation. Afterwards, cells were replenished with drug-free media and incubated for an additional 20 h before the determination of cell proliferation. The values plotted represent an average (± SD) of two independent experiments. ROS: Reactive oxygen species.