Programmed death-ligand 1 (PD-L1), also known as CD274, is a transmembrane protein that binds to the inhibitory receptor PD-1 on T cells and elicits T cell anergy, leading to immune suppression [57], Many cancer cells upregulate PD-L1 surface expression to escape immune surveillance [58–60]. The gene discussed is PDCD1; the disease is cancer.