CD274 and cancer: It was previously shown in cancer cell lines that the IFN-γ-mediated induction of PD-L1 mRNA expression affected PD-L1v1 mRNA and PD-L1v4 mRNA expression levels differently, and accordingly, IFN-γ could influence the PD-L1v4/PD-L1v1 mRNA ratio [36,37].