Irradiation-induced activation of caspases and apoptosis.

Cells were exposed to irradiation (100 Gy) and further cultured for 6 hours. (A) Activity of caspase-3. (B) Activity of caspase-9. (C) Percentage of apoptosis. Apaf-1–transfected cells were statistically significantly more sensitive than wild-type cells (*P < .001).