CXCR4 and neoplasm: Bone-homing tumor cells tend to overexpress chemokine receptors, CXCR4, CXCR6, and CXCR2 that subsequently contribute to the movement of the tumor cells from the bone marrow to other organs by seeking CXCL12, CXCL-16, and CXCL-10 respectively (47).