CXCR4 and cancer: Although the detailed mechanism(s) underlying the migration and homing of MSCs to tumors are not well documented, MSCs have a similar homing mechanism to inflammatory cells, hematopoietic stem cells, and cancer cells in that they utilize the same adhesion molecules and cytokines/chemokines, most notably the CXCR4-CXCL12 receptor-ligand binding system [63, 64].