Programmed cell death ligand-1 (PD-L1) is a type I transmembrane glycoprotein expressed in many tumor types, including melanoma, brain tumor, lung cancer, breast cancer, gastric cancer, ovarian cancer, pancreatic cancer, and renal cancer [[1], [2], [3], [4], [5], [6], [7]]. The gene discussed is CD274; the disease is gastric cancer.