For example, markers such as platelet-derived growth factor receptor alpha/beta (PDGFRα/β), CD90/THY1, podoplanin (PDPN), α-SMA, fibroblast-specific protein 1 (FSP-1), fibroblast-activating protein (FAP), fibronectin 1 (FN-1), vimentin (VIM), CD29, CD10 or G protein-coupled receptor 77 (GPR77) are expressed by breast cancer CAFs, although not exclusively. The gene discussed is C5AR2; the disease is breast cancer.