APAF1 (apoptotic peptidase activating factor 1) is the molecular core of the apoptosome, a multiprotein complex that mediates the mitochondrial pathway of apoptosis 1. Upon cytochrome c release from mitochondria, oligomeric APAF1 binds cytochrome c and ATP to activate pro-caspase-9, which subsequently activates caspase-3 and executes programmed cell death 2. APAF1 represents the human homolog of C. elegans CED-4, highlighting evolutionary conservation of apoptotic machinery 2. Beyond canonical apoptosis, APAF1 participates in pyroptosis through formation of the Apaf-1 pyroptosome in response to mitochondrial permeability transition, activating caspase-4 and GSDME-mediated cell death under sterile conditions 3. APAF1 dysregulation contributes to multiple pathologies. During development, APAF1 deficiency causes embryonic lethality with impaired neuronal apoptosis and developmental abnormalities 4. In cancer, APAF1 mutations promote malignant transformation; conversely, lncRNA-mediated APAF1 inhibition blocks apoptosome assembly and induces multidrug resistance in gastric cancer 5. APAF1 upregulation associates with sepsis progression and correlates with altered immune infiltration 6. These findings establish APAF1 as a critical regulator of cell death with therapeutic implications in cancer and inflammatory diseases.