CD274 and neoplasm: PD-L1 is expressed by various cell types such as immune cells and tumor cells after interacting with cytokines such as interferon- (IFN-) Y. Following interaction with cytokines such as interferon- (IFN-) Y, the PD-1/PD-L1 pathway by various cell types, including immune and tumor cells, maintains immune system homeostasis in vivo and infects it or inflammation [9].