Then, we evaluated their expression in leukaemia cell lines characterized by a different uPAR/CXCR4 expression, low in KG1 cells, derived from an M0 subtype of AML, and high in pro-monocytic THP-1 and U937 cells, showing an inverse expression of selected miRs, consistent with the hypothesis that these miRs directly regulate uPAR/CXCR4 expression. This evidence concerns the gene CXCR4 and leukemia.