The key ligands involved in MSC homing include chemokine receptors CCR2, CXCL12, and CXCR4 and adhesion ligands, such as SELPLG and SELP, among which CXCR4 is one of the most important molecules mediating the tumor-homing effects of MSCs [14]. The gene discussed is CXCR4; the disease is neoplasm.