CXCR4 and B-cell chronic lymphocytic leukemia: The CXCL12/CXCR4 interaction, which is relevant in inducing CLL cell survival, proliferation and chemotaxis, also has remarkable influences on bone remodeling: through CXCR4, CXCL12 binding promotes osteoclastogenesis and induces osteogenic differentiation of mesenchymal stromal cells in cooperation with bone morphogenetic protein (BMP) signaling [37,41,42].