Cytochrome

c–mediated activation of caspases. S-100 was prepared from the wild-type and Apaf-1–transfected cells. Wild-type cells are indicated as Apaf-1 (−), and Apaf-1–transfected cells are indicated as Apaf-1 (+). (A) Cytochrome c–mediated procaspase-9 activation. The increased activity of caspase-9 in Apaf-1–transfected cells was compared with their wild type (*P < .0001). Processing of procaspase-9 was confirmed by immunoblotting. Caspase-9 precursors are indicated by an asterisk, and the processed caspase-9 are indicated by an arrowhead. (B) Cytochromec–mediated procaspase-3 activation. *P < .0001; **P < .01. Processing of procaspase-3 protein was indicated by immunoblotting. Caspase-9 precursors are indicated by an asterisk, and β-actin is indicated by an arrow.