CXCR4 expression at the plasma membrane is dynamically regulated by its downmodulation in the presence of high ligand concentrations and its recycling when these decrease [30], and it was previously demonstrated that enhanced receptor recycling contributes to the increased surface CXCR4 levels on CLL cells and enhanced migratory responses [31]. Here, CXCR4 is linked to B-cell chronic lymphocytic leukemia.