CD274 and extranodal nasal NK/T cell lymphoma: Our findings included the following: (1) PD-L1 expression positively correlated LMP1 expression at both protein and mRNA levels in NKTCL and NK cells; (2) PD-L1 expression was upregulated by LMP1 through the MAPK/NF-κB pathway; and (3) the levels of PD-L1 expression on tumor tissues and the pre-treatment concentration of serum soluble PD-L1 correlated with the survival in early-stage NKTCL patients treated with asparaginase-containing chemotherapy combined with RT.