In particular, miR-15a and miR-16-1 genes, often down-regulated or deleted in approximately 68% of CLL cases, were found to target the B-cell lymphoma 2 (BCL-2) gene, providing a mechanistic link between their downregulation or deletion and the apoptotic resistance commonly observed in CLL cells. This evidence concerns the gene BCL2 and B-cell chronic lymphocytic leukemia.