Programmed death ligand 1 (PD-L1; also known as CD274 or B7-H1) is an immunosuppressive molecule expressed on the surface of tumor cells and immune cell membranes that interacts with programmed death 1 (PD-1) receptors on the surface of T lymphocytes to negatively regulate T cell functions [21]. The gene discussed is CD274; the disease is neoplasm.