TNFSF10 and neoplasm: These disappointing results can be attributed to the apoptosis resistance mechanisms present in many primary tumor cells and may comprise the constitutive upregulation of the anti-apoptotic proteins operating at different levels of the TRAIL/TRAIL-R signaling cascades like decoy/regulatory receptors, FLIP, Bcl-xL, and IAP (Hinz et al., 2000; Trauzold et al., 2001; Trauzold et al., 2003; Lemke et al., 2010).