CYCS encodes cytochrome c, a dual-function protein essential for both cellular respiration and apoptotic signaling. In its primary role, CYCS functions as an electron carrier in the mitochondrial respiratory chain, facilitating electron transport from complex III to complex IV during cellular respiration 1. Upon apoptotic stimuli, CYCS is released from mitochondria into the cytosol, where it binds to APAF1 to form the apoptosome complex, triggering caspase-9 activation and subsequent apoptotic cell death 23. Recent studies have revealed additional roles for cytosolic CYCS beyond apoptosis. CYCS forms a distinct complex with INPP4A that prevents ferroptosis by enhancing phosphatidylinositol-3-phosphate formation, which protects against lipid peroxidation and plasma membrane rupture 4. The protein undergoes post-translational modifications including lysine succinylation at residues K28/K40, which is crucial for its role in regulating erythropoiesis 5. CYCS is also implicated in pyroptosis through the BAX-caspase-GSDME signaling pathway, where mitochondrial release of CYCS activates caspase-3, leading to GSDME cleavage and pyroptotic cell death 2. These findings establish CYCS as a central regulator of multiple cell death pathways, with therapeutic implications for cancer treatment and blood disorders.