CD274 and cancer: Moreover, radiation treatment is also able to downregulate anti-cancer immunity associated with increased tumor infiltration of immunosuppressive cells, such as myeloid-derived suppressive cells [5], regulatory T cells [6] and cancer-associated fibroblasts [7], and upregulate immunosuppressive molecules, such as programmed cell death ligand 1 (PD-L1) [8] and transforming growth factor-β (TGF-β) [9].