Abstract:Non-coding RNAs (ncRNAs) are RNA molecules that do not serve as template for translation. They participate in a myriad of biological processes and play crucial regulatory roles. NcRNAs have been found to regulate translation and splicing， serve as ribozymes， modulate DNA replication and gene transcription， dictate development and cell differentiation. In this review， we focus on the regulation of ncRNAs in the transcription of RNA polymerase II in mammalian cells.