Upon coculture of WT, IFN-γ−/−, or Prf1−/− TRP1high CD8 T cells with C2VTrp1 tumor cells, we observed a decrease in cytotoxicity from TRP1high T cells deficient in IFΝ-γ and no loss in cytotoxicity from TRP1high T cells deficient in perforin (Fig. 4B). The gene discussed is PRF1; the disease is neoplasm.