CD274 and neoplasm: Extensive studies suggest that MSCs inhibit both T cells proliferation [109] by secreting Prostaglandin E2 (PGE2) and programmed death ligand-1 (PD-L1) [110] and T cells anti-tumor immunity [38] by secreting immunosuppressive cytokines, such as IL-4 and IL-10 [111], which are not necessarily related to the MSC source.