In this manner, numerous chemoattractants, such as transforming growth factor β (TGF-β), vascular endothelial growth factor (VEGF), RANK-ligand, and C-X-C chemokine receptor type 4 (CXCR4) have been associated with the homing of circulating tumor cells to bone and providing a fertile ‘soil’ for these cells in secondary sites [2,3,4]. Here, CXCR4 is linked to neoplasm.