BID (BH3 interacting domain death agonist) is a pro-apoptotic BCL-2 family protein that functions as a critical mediator of caspase-dependent apoptosis. BID is cleaved by multiple proteases including caspase-8, caspase-2, granzyme B, calpains, and cathepsins 1. Upon cleavage, truncated BID (tBid) translocates to the mitochondrial outer membrane where it induces permeabilization through a mechanism dependent on pro-apoptotic BAX and BAK proteins 2. This mitochondrial outer membrane permeabilization (MOMP) triggers the release of cytochrome c and engages the intrinsic apoptotic pathway 1. Structurally, BID functions as both a BH3-only protein and exhibits mechanistic similarities to multi-BH region proteins like BAX, with its N-terminal inhibition relieved upon proteolytic processing 1. BID plays essential roles in death receptor-mediated apoptosis and stress-induced cell death. Recent evidence demonstrates that caspase-2-activated BID is required for PIDDosome-driven apoptosis in response to centrosomal abnormalities and genotoxic stress 34. Reduced BID expression correlates with malignant transformation in endometrial tissues, suggesting its downregulation facilitates neoplastic progression 5. These findings establish BID as a sentinel protein that integrates multiple death signals to activate mitochondrial-dependent apoptosis.