The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.
RNA interference (RNAi) has been shown to spread from cell to cell in plants and in Caenorhabditis elegans, but it does not spread in other organisms, such as Drosophila. A recent report demonstrates that a membrane channel, encoded by the gene sid-1, is responsible for the spreading of RNAi between cells.