Effects of As₂O₃ and DHA on the cell-cycle status and apoptosis. 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). Thereafter, the cells were stained with propidium iodide (PI), and the percentage of cells with hypodiploid DNA content, representing the proportion of apoptotic cells, was determined by means of flow cytometry.