CXCL12 and cancer: Furthermore, TA-MSCs release mitogens such as epithelial growth factor (EGF), hepatocyte growth factor (HGF), EGF family members, insulin-like growth factor-1 (IGF-1), and different members of the fibroblast growth factor (FGF) family, which are able to directly stimulate cancer cell proliferation, and they release chemokines, such as stromal cell-derived factor-1 (SDF-1/CXCL12) able to trigger the recruitment of progenitor cells or the proliferation of stem cells (Franco et al., 2010; Rasanen and Vaheri, 2010).