In this microenvironment scenario, cancer cells produce a cocktail of growth factors (EGF, HGF, SCF, IGF-1, VEGF, PDGF or βFGF), cytokines (IL-1β, IL-8, TNF-α or TGF-α) and chemokines (CCL2, CCL5, CCL22 or CXCL12) that induce the recruitment of MSCs to the tumor locations, as it has been shown for different types of cancer such as breast, ovarian, gastric, pancreatic, colorectal, skin cancer or melanoma (for review, [8]). The gene discussed is CXCL12; the disease is cancer.