Abstract: The miR-17-92 cluster, consisting of six individual microRNAs, including miR-17, miR-20a,miR-18a, miR-19a, miR-19b and miR-92a-1, is a kind of typical oncogenic polycistron microRNA. MiR-19 (containing miR-19a and miR-19b), as the key oncogenic component in miR-17-92 cluster, is overexpressed in human cancers including lymphomas, leukaemia, lung cancer, breast cancer and multiple myeloma, and has been one of research focus in recent years. It is found that miR-19 promotes tumor growth，invasion and metastasis through negative regulation of target genes such as PTEN, PP2A, Bim,SOCS1, and is correlated strongly with PI3K-AKT-mTOR pathway. MiR-19 plays an important role in tumor genesis and development.

Key words: miR-19, Neoplasms, Lymphoma, Leukemia