CXCR4 and B-cell chronic lymphocytic leukemia: These signals are propagated through diverse receptors, such as CD40[8], Toll-like receptors (TLR)[9], CXCR4[10] and the B cell receptor (BCR)[11], which activate downstream signaling pathways that ultimately promote proliferation, modulate cell adhesion and chemotaxis and protect CLL cells from spontaneous and drug-induced apoptosis.