APAF1, also named as Apoptotic protease-activating factor 1 or KIAA0413, is a 1248 amino acid protein, which contains one CARD domain, contains one NB-ARC domain and Contains fifteen WD repeats. APAF1 localizes in the cytoplasm and is widely expressed in many tissues. Highest levels of expression is in adult spleen, peripheral blood leukocytes, in fetal brain, kidney and lung. Oligomeric APAF1 mediates the cytochrome c-dependent autocatalytic activation of pro-caspase-9 (Apaf-3), leading to the activation of caspase-3 and apoptosis.