CBFβ-SMMHC slows apoptosis in Ba/F3 cells exposed to IR or VP-16. (A) MTCB6, MTINV-2, or MTINV-3 cells were cultured in the absence or presence of zinc for 18 hours. The cells were then removed from IL-3 and irradiated to 10 Gy, and 6 hours later the cells stained with PI and FITC-Annexin V and subjected to FACScan analysis. After irradiation, cells initially in zinc were continued in zinc. Data from a typical experiment are shown. The cluster of cells that excluded PI and was determined to be alive is boxed in the upper left panel. (B) The proportion of parental Ba/F3, MTCB6, MTINV-2, or MTINV-3 cells surviving 10 Gy or IR followed by culture in the absence of IL-3 for 6 hours, surviving 8 μg/mL VP-16 for 6 hours in the absence of IL-3, or surviving 3 μg/mL VP-16 for 18 hours in the presence of IL-3 are shown. Ratios of the proportion of cells surviving in the presence of zinc to the proportion of cells surviving in the absence of zinc were calculated for each cell line in each experiment. Results shown are the mean and SE from three experiments.