CD274 and cancer: The role played by CAFs in tumor immunity is fourfold: (1) they orchestrate the dense fibrotic stroma that forms a physical barrier for immune cell infiltration into the tumor, (2) they are the predominate source of immunosuppressive molecules, such as cytokines/chemokines and growth factors, which suppress immune cell activation, (3) CAFs help cancer cells to express high levels of immune checkpoint blockades such as PDL-1, and (4) activated CAFs form a physical trap for checkpoint blockades such as PDL-1 antibody due to the high-level expression of PDL-1 on CAFs.