CD274 and Epstein-Barr virus infection: Therefore, we explored whether IFN-γ could cooperate with EBV to promote PD-L1 expression after IFN-γ (10 ng/mL) stimulation and found that IFN-γ demonstrated functions in both EBV-negative and EBV-positive cells; however, EBV infection further enhanced the induction of PD-L1 expression by IFN-γ (Supplementary Fig. 2a).