The mode of action of γδ T cells in an anti-tumor response comprises direct cytolytic activity via NKG2D, FcyRIII, Fas/Fas-ligand, DNAM-1 receptor-ligand interaction and the TNF related apoptosis inducing ligand (TRAIL) pathway resulting in production of perforins, granzymes, IFN-γ and TNF-α (4, 5, 18–23). The gene discussed is TNF; the disease is neoplasm.