This vector has been replaced by the newer pLVTHM vector, which allows for direct cloning of shRNA. For pLVTH: if you have your shRNA already in pSUPER (or any other plasmid under control of PolIII promoter) you may use EcoR1-Cla1 sites to replace H1 promoter in pLVTH with H1-shRNA cassette from pSUPER (or other plasmid). Please note that there is an additional ClaI site in this vector that is blocked by Dam methylation. This plasmid needs to be grown in a Dam+ bacteria strain if you wish to use ClaI for cloning. Article: Conditional suppression of cellular genes: lentivirus vector-mediated drug-inducible RNA interference. Wiznerowicz M et al. (J Virol. 2003 Aug . 77(16):8957-61.