CXCR4 and B-cell chronic lymphocytic leukemia: In addition, co-culture of CLL cells induced a downregulation of the expression level of CXCR4 (mean MFI of CXCR4 expression in co-culture vs. in suspension: 247.6±41.23 vs. 741.0±160.3, P<0.001) while CXCR5 and CCR7 expression levels were not significantly modulated (mean MFI of CXCR5 expression in co-culture vs. in suspension: 1122±121.0 vs. 906.6±94.32, P=n.s.; mean MFI of CCR7 expression in co-culture vs. in suspension: 221.4±13.79 vs. 225.0±23.43, P=n.s).