These targets include both tumor suppressors (p21, Bim, PTEN, Rb2/p130, Rbl2) as well as oncogenes (E2F1, AIB1) suggesting that the miRNAs of the miR 17–92 cluster can act as both oncogenes or tumor suppressors by modulating cell proliferation in a cell-type-specific manner depending on the set of target mRNAs that are expressed [42,49,59-62]. This evidence concerns the gene E2F1 and neoplasm.