ATO-induced apoptosis and cell cycle arrest in IM9, HS-Sultan, U266, and ARP-1 cells.

(A) Apoptosis. (B) Cell cycle arrest. Cells were cultured for 0, 4, 8, 16, 24, 30, and 38 hours with 0 to 6 μM ATO. Apoptosis was determined by the annexin V method and cell cycle distribution by the propidium iodide staining method. For additional experimental details, see legends to Figures 1 and 2 and “Materials and methods.” Representative results from at least 3 different experiments are shown.