TNF and head and neck squamous cell carcinoma: Although studies by other groups indicate that the cytotoxic effects of SMAC mimetics are potentiated by death ligands such as TNFA and TRAIL in HNSCC (25, 27), we did not observe dramatic increases in birinapant-induced necroptosis in the presence of exogenous death ligands in the MOC1 or UMSCC 17A cell lines (Supplemental Figures 2 and 3), a phenomenon that might be explained by low activity of death receptor signaling in these lines (35).