Figure 6.

The caspase inhibitor Z-VAD attenuated the ABT-263-induced decrease in the surviving fraction of irradiated A549 cells. (A) The treatment procedure is shown. A549 cells irradiated at 6 Gy were cultured for 24 h prior to the addition of ABT-263 (5 μM) to the culture. After two days of culture, the medium containing Z-VAD and ABT-263 was replaced with fresh medium. The cultures were continued until colonies were formed. Then, the colony number was counted. (B) The surviving fraction of A549 cells is shown. Data are presented as the mean ± SD of independent experiments. ** p < 0.01.