CD274 and neoplasm: PD-L1 is also known as differentiation 274 cluster (CD274), an important B7 family member.19Being an inhibitory ligand, the PD-L1 represents an essential immune checkpoint that has key roles to play in regulating cellular, adaptive, and humoral immune responses.20PD-L1 binds to programmed death of cell protein 1 (PD-1) receptor, which transmits negative regulatory signals to bolster tumor immune evasion and stimulate tumor antigen-specific T cells' apoptosis and immune incompetence.