CXCL12 and cancer: On the other hand, CAFs can enhance the metastatic potential of cancer cells by the induction of EMT, through the paracrine secretion of transforming growth factor-β (TGF-β),which promotes cancer cell invasion [88,89] and the differentiation of CAFs in an autocrine fashion [90], CXCL12 [91], interleukin 6 (IL-6) [92,93], or matrix metalloproteinases (MMPs) [94].