Moreover, MSCs can migrate to the tumor site through the interaction of a variety of chemokine receptors (such as CCR-1, CCR-2, CCR-3, CCR-4, CCR-5, CCR-7, CXCR-1, CXCR-2, CXCR-3, CXCR-4) on MSCs and cytokines or chemokines (such as endothelial cell selectin, MMPs, IL-8, PGDF-AB, IGF-1, VEGF) secreted by solid tumors [138–140]. The gene discussed is CXCR4; the disease is neoplasm.