For example, CAFs secrete transforming growth factor-β (TGF-β), stromal-derived factor 1 (SDF-1), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF) and interleukins (IL), which generate tumour vasculature, promote immunosuppression and enhance drug resistance (10). This evidence concerns the gene CXCL12 and neoplasm.