Abstract: MicroRNAs (miRNAs) constitute a class of endogenous, small noncoding RNA with the length of 18~25 nucleotides in plants and metazoans. Those small RNAs were demonstrated to play important roles in a wide range of biological processes, including cell migration and cancer metastasis. What is noted, it was showed that a large number of miRNAs were deregulated in cancer samples. More recently, several of the including miR-10b, miR-373, miR-520c, and miR-520e and miR-31 have been experimentally demonstrated as metastatic related miRNAs. However, one of central questions is how many miRNAs contribute to cancerogenesis, especially metastasis. In this talk, I will present our recent work regarding the high throughput screen of functional miRNA genes regulating cell migration. I will also show the primary screen results and discuss the molecular mechanism of a couple of miRNAs in the process of colon metastasis.