Coding sequence of microRNAs may be present in the introns of split gene, and it can also exist in the intergenic non-coding regions.()
Small RNA molecules produced endogenously are called microRNAs, small RNAs that are transformed into cell exogenously are called siRNA.()
A lot of genes can be regulated by one kind of miRNA, some of which are degraded under the regulation of miRNA, while the translation of some genes are only be inhibited.()