The function of APAF1 (apoptotic peptidase activating factor 1, Ensembl gene identifier ENSG00000120868) is as follows. Oligomeric Apaf-1 mediates the cytochrome c-dependent autocatalytic activation of pro-caspase-9 (Apaf-3), leading to the activation of caspase-3 and apoptosis. This activation requires ATP. Isoform 6 is less effective in inducing apoptosis. .