Effects of As₂O₃ and DHA on the mitochondrial membrane potential of HL-60 cells. Cells were treated with 1 μM As₂O₃, 25 μM DHA, or the combination of both substances for 18 hours. For comparison, cells were treated with 25 μM OA ± 1 μM As₂O₃ or left untreated (control). To determine the mitochondrial membrane potential, cells were stained with DiOC6 and analyzed by flow cytometry. Values represent percent of cells with reduced mitochondrial membrane potential.