ATO synergizes with APO2/TRAIL in the induction of apoptosis in partially resistant myeloma cells.

(A) HS-Sultan, (B) ARP-1, (C) IM9, and (D) U266 cells were cultured for 2 days with 0, 2.5, 5, and 10 μM ATO with or without 25, 50, and 100 ng/mL APO2/TRAIL. Apoptosis was determined by the annexin V method. For additional experimental details, see the legend to Figure 1 and “Materials and methods.” Bars represent SD from at least 3 independent experiments. Note the clear synergy between ATO and APO2/TRAIL in IM9 and HS-Sultan cells expressing wt p53.