FADD and neoplasm: Because 3LL cells failed to secrete cytokines in response to CD95L in vitro (Figures S4F–S4H), we conclude that endogenous TRAIL/TRAIL-R induces secretion of CCL2 from tumor cells in a FADD-dependent manner and that this CCL2 is required to facilitate the accumulation of tumor-promoting myeloid cells in vivo.