The proposed conference, Mechanisms of Signal transduction, will be the fifth Gordon Conference on this topic. Since its inception in 1999, this has been a key, truly international meeting for scientists studying small GTPases, their effectors, and their regulators, all of which regulate normal cellular processes as diverse as proliferation, polarity, migration and gene expression, and that contribute to disease processes such as cancer. The conference will be held September 16-21, 2007, at Magdelene College in Oxford, UK. These conferences have provided a unique forum for addressing important questions of cell biology that regulate, or are regulated by, members of the Ras superfamily of GTPases. These conferences are arranged around biological themes to enhance the principal objective, which is to stimulate cross-pollination of ideas among a diverse group of cell and structural biologists and biochemists by bringing them together in an intimate setting to share the latest developments in their fields. There are 38 invited speakers from the United States, Europe, and Japan, with additional short presentations to be selected from submitted abstracts. Special attention has been paid to inclusion of women, and of young and minority investigators. The 8 oral sessions and 4 poster sessions will be enhanced by informal interactions at the conference site to develop new ideas and collaborative relationships.