enetic analysis in model organisms such as yeast, C. elegans and fruit flies have yielded many fundamental discoveries in basic biology which ultimately resulted in breakthroughs in our understandings of human diseases including cancer. The lack of genetic tools in mammalian system has significantly hampered genetics studies in human cells. The advent of RNAi technology has made it possible to conduct such analysis.PURPOSEWe aim to develop new mammalian vector systems to express shRNAs and cDNAs efficiently. This will enable us to rapidly introduce defined genetic changes into cells to create the desired genotype.SIGNIFICANT MATERIALS AND METHODSExpression vectors for shRNAs and cDNAs.FY2012 ACCOMPLISHMENTWe have established a vector system and validated shRNAs against tumor suppressors. We have constructed cell lines with defined genetic perturbations to analyze the functional consequences of these genetic alterations.