PRF1 and cancer: After coculture of Ppard−/− CTLs with cancer cells, we observed higher granzyme B levels in cancer cells than those cocultured with wild-type CTLs (Fig. 1D), suggesting that Ppard−/− CTLs express more granzyme B because cancer cells do not express granzyme B. Indeed, Ppard−/− CTLs showed increased expression of granzyme B, perforin, and secreted IFNγ compared with wild-type cells (Fig. 2B; Supplementary Fig. S2B).