ATO-induced apoptosis in myeloma cells expressing mutated (A) or wt (B) p53.

Cells were cultured for 2 days with 0 to 10 μM ATO. Apoptosis was determined following 48 hours of treatment, by the annexin V method. NB4 cells were used as a reference for an ATO-sensitive cell line. For more experimental details, see “Materials and methods.” Bars are ± SD of at least 3 experiments. Note the clear difference in sensitivity to apoptosis between cells expressing wt or mutated p53.