RNA interference or RNAi represents an extremely useful technology in medical research to study cellular mechanisms implicated in cancer formation and maintenance. Recent scientific data supports the great potential of RNAi as a therapeutic agent for curing various types of cancer and other human diseases. In order to use the full potential of RNAi, it is extremely important to get a complete understanding of this cellular pathway. To achieve this task, we will first utilize the round worm as a model system to rapidly: 1) elucidate the biochemical steps critical for the RNAi pathway and; 2) identify new cellular components of the RNAi pathway. The discoveries made with this simple animal model will then be tested in a human cell culture system. This study will contribute to a better use of RNAi as a molecular tool essential for medical research and to the development of RNAi-derived therapeutic agents.