Moreover, only two out of six samples of CLL cells showed a significant CXCR4 and RAC1 increased mRNA level in response to both TGFß (SMAD-activating signal) and WNT-signalling activation in vitro (Supplementary Fig. S5F) as described from previous reports28. This evidence concerns the gene CXCR4 and B-cell chronic lymphocytic leukemia.