A polycistronic miRNA cluster miR-17-92 plays a role in the control of cell proliferation and angiogenesis. This cluster consists of seven miRNAs: miR-17-5p, miR-17-3p, miR-18a, miR-19a, miR-19b, miR-20a, and miR-92. Like E2F1 gene, the cluster is transcriptionally activated by the proto-oncogene c-Myc. Because two of the expressed miRNAs, miR-17-5p and miR-20a, repress the translation of E2F1, the level of E2F1 protein is modulated by this feedback mechanism. Therefore, the accumulation of excessive amounts of E2F1 can be prevented and the states of cells towards apoptosis or cell division can be controlled. In addition, c-MYC-mediated induction of the miR-17-92 cluster promotes angiogenesis through the down-regulation of the anti-angiogenic thrombospondin-1 and related proteins, such as connective tissue growth factor 2. Furthermore, a recent study indicates that the cluster is significantly up-regulated at the clonal expansion stage of adipocyte differentiation. The miR-17-92 cluster has been implicated as the oncogenes in numerous tumor types. Effective monitoring of the expression of the clustered miRNAs can help us better understand how the alteration of the cluster contributes to development of cancers and shed light on the molecular mechanisms of miRNA function