This project is developing technology that allows the selective manipulation of gene expression in human cancer cells derived directly from children with pediatric brain tumors. These efforts will permit deciphering of the signal transduction pathways critical for brain cancer cell growth and survival and allow the development of novel therapeutic approaches in affected children. Although such methods of discovery have been utilized in model organisms, similar approaches in human systems have not been feasible due to the inability to easily manipulate gene expression. The work in this initiative takes advantage of a newly defined system for manipulation of RNA expression termed RNAi, a discovery that was awarded the 2007 Nobel Prize in Physiology or Medicine. Although initial experiments will be focused on pediatric brain cancer (see Leonard, Rubin), it is apparent that once produced and made available to the community, this reagent will allow individual investigators to ask innovative biological questions relevant to gene function in primary cultures. This invaluable library is available to the entire Washington University community.