CD274 and nasopharyngeal carcinoma: IHC experiments further confirmed the high expression of PD-L1 in 52 additional NPC samples (39 EBV-positive and 13 EBV-negative cases) compared with that in 36 non-tumor NPE tissues (Fig. 1b), and in 40 GC tissues (25 EBV-positive and 15 EBV-negative) compared with that in 20 normal gastric mucosa tissues (Fig. 1c).