BCL2 and neoplasm: Although the underlying mechanisms need further clarification, regulation of endogenous and exogenous TRAIL sensitivity by tumor—stroma cell interactions frequently involve regulation of TRAIL/TRAIL-R levels including decoy receptors and OPG, and NF-κB-dependent regulation of intracellular pro- and antiapoptotic factors such as Bcl2 family members and IAPs together with secretion of cytokines in feedforward or feedback loops.