After the cells are exposed to apoptosis-inducing factors (e.g., tumor necrosis factor, TNF-α) stimulated by apoptotic signals, BID is cleaved by activated caspase-8 to form a truncated BID fragment (tBID) in the inflammatory or tumor environment, which enters the mitochondria to induce the release of cytochrome c and other pro-apoptotic molecules to regulate apoptosis. Here, BID is linked to neoplasm.