CD274 and melanoma: Expression of PD-L1 has been reported in tumor cells of different types of cancer, including glioblastoma, ovarian cancer, renal cell carcinomas, squamous cell carcinoma of the head and neck, colon cancer, breast infiltrating ductal carcinoma, esophageal cancer, non-small cell lung cancers and melanoma [6,8,12,15,16,17,18,19,20].