RNA interference(RNAi) is mediated through small double-stranded RNA molecules(small interfering RNAs,siRNAs),and siRNA can induce special mRNA degradation.The special gene is interfered by post-transcriptional gene silencing.It is a monitoring mechanism widely found in living nature to defend the virus infection,and regulate the expression of protein-coding genes.RNAi is now a powerful instrument for functional genomic analyses and signal transduction pathways,and it will be a potentionally useful method in highly specific dsRNA based gene-silencing therapeutics.