Effects of As₂O₃ and DHA on apoptosis of HL-60 cells. Cells were treated for 24 hours with 1 μM As₂O₃,25 μM DHA, or 1 μM As₂O₃ and 25 μM DHA in combination. For comparison, cells were treated with 25 μM OA ± 1 μM As₂O₃ or left untreated (control). After treatment, the cells were stained with annexin V/propidium iodide and analyzed by flow cytometry. Values are the mean (± SD) of 3 separate experiments.