Growing evidence suggests that tumor-derived growth factors, such as transforming growth factor beta-1 (TGF-β1), platelet-derived growth factor (PDGF), and basic fibroblast growth factor (bFGF), convert resident fibroblasts into CAFs due to activation of autocrine activating signaling loops mediated by CAF-derived TGF-β and stromal cell-derived factor 1 (SDF-1) cytokines. This evidence concerns the gene CXCL12 and neoplasm.