FIGURE 1.

Effects of Cholix on cell viability. A, cells (1 × 10⁴ cells/well) in a 96-well dish were cultured for 48 h and then incubated with indicated concentrations of wild-type or mutant Cholix for 24 h. Cell viability was determined using a Cell Counting kit. Data are the means ± S.D. value from three separate experiments. Student's t test was used for comparisons with the untreated cells. ^#, p < 0.1 and *, p < 0.01, respectively. B, effects of pretreatment with a general caspase inhibitor on cytotoxicity of Cholix. Cells (1 × 10⁴ cells/well) in a 96-well dish were grown for 48 h and then pretreated with 20 μm general caspase inhibitor (Z-VAD-FMK) for 40 min, followed by incubation with Cholix (10 μg/ml) in the presence or absence of Z-VAD-FMK. Cell viability was determined as described above. Data are the means ± S.D. value from three separate experiments.