To provide a possible mechanistic explanation for the reduced tumor growth in TNFR1 KO mice and given the increased frequency of CD8+ infiltrating T cells, we explored the ex vivo functionality of TNFR1 KO vs. WT activated CD8+ T cells cultured in the presence of B16.F1 melanoma cells conditioned media (B16.F1 CM). The gene discussed is CD8A; the disease is melanoma.