CD274 and cancer: Besides turning invisible to the immune system, cancer cells can inhibit the immune response either by directly producing immunosuppressive factors, such as the immune checkpoint molecule PD-L1, or recruiting cells such as the cancer-associated fibroblasts, Tregs, M2 polarized macrophages or myeloid-derived suppressor cells (MDSC) that secrete immunosuppressive cytokines, such as IL-10, TGF-β, or VEGF, supporting then the growth of the tumor [210,221].