PDCD1 and neoplasm: To investigate whether T cells contribute to the delay of tumor growth in the OT-1-Lag3−/−Pdcd1−/− mice, tumor infiltrating T cells (TILs) from the tumor bed and tumor associated T cells (TALs) from ascities were isolated from tumor bearing OT-1-Lag3−/−, OT-1-Pdcd1−/−, and OT-1-Lag3−/−Pdcd1−/− mice.