The review analyzes the stages of microRNA discovery. The issues of siRNA synthesis and the significance of this class of RNA are touched upon. Now an atlas of human and mouse microRNAs has been created by scientists from 20 countries around the world. The microRNA site (miRBase) also functions and provides information on all open miRNAs, their genomic localization, sequence and expression. The current version of the database contains information on 28 645 microRNAs (of which 2588 human beings) and is available at http://mirbase.org.
