Once the clone containing the desired DNA Insert is identified.It is multiplied in E.coli to obtain sufficient number of copies to be used in one or more of the following ways. (1) It canbe used for a structural analysis of the insert e.g DNA sequencing, chromosome walking etc. (2) IT may be introduced into a bacterium like it subtilis for production of the protein encoded by the insert since this host secretes protein into the medium which allows easy purification (3) It can be introduced into a eukaryotic host. e.g yeast, animal cells plants etc. either to investigate the function of the insert or (4) to integrate it into the host genome to achieve one of many diverse objective the aims, techniques and the achievements.