Abstract: Recent Advances in the Research on the Relationship between miRNA-21 and CancerYang YANG, Chunsheng KANGCorrespondence to: Chunsheng KANG, E-mail: kang97061@yahoo.comDepartment of Neurosurgery, Tianjin Medical University General Hospital, Laboratory of Neuro-Onoclogy, Tianjin Neurological Insti-tute, Tianjin 300052, ChinaThis work was supported by National Natural Science Foandation of China (No.30971136) and Science and Technology Planning Pro-gram of Tianjin (No.09JCZDJC17600)Abstract MicroRNAs (mRNAs) are a class of endogenous small noncoding single-stranded RNAs that negatively regulate geneexpression at the post-transcriptional level. MicroRNAs are involved in diverse biological processes, including development, cell differ-entiation and cell death. It was found that miRNA-21 played an important role in the course of oncogenesis. The expression of miR-NA-21 is significantly upregulated in different kinds of solid tumors. It is involved in cell proliferation, cell invasiveness, angiogenesisand other biological behaviors. This review summarizes the current knowledge concerning the expression and location of miRNA-21and the regulatory network related to miRNA-21 in cancer.Keywords miRNA-21; Cancer; Signal transduction pathway; Transcription