CD274 and neoplasm: We prepared splenic CD8+ T cells from OT-I TCR Tg (specific for Ovalbumin 257-264 [OVA257–264] loaded on H-2Kb) Rag2-deficient (Rag2−/−) PD-1-deficient (Pdcd1−/−) mice, reconstituted by hPD-1 (Supplementary Fig. 4d), and examined the cytotoxicity of these hPD-1-expressing T cells by coculture with the H-2Kb tumor cell line, EL-4 cells, without or with hPD-L1 expression (Supplementary Fig. 4e).