DATS-induced apoptosis is associated with ROS generation in U937 cells. Cells were incubated with 20 μM of DATS for 48 h after pretreatment with or without 10 mM of NAC. Cells were evaluated for sub-G1 DNA content using a flow cytometer (A) and cell viability was determined using the MTT assay (B). Data are expressed as overall means ± SD from three independent experiments. Statistical significance was determined using the Student’s t-test (*P < 0.05 vs. vehicle control). (C) Following incubation of cells under the same conditions, cells were fixed, stained with DAPI, and the nuclear morphology was then photographed under fluorescence using a blue filter. Magnification, ×400.