The GTPase switch appears to be almost as old as life itself, and nature has adapted it to a variety of purposes. This two-volume work surveys the major classes of GTPases, including their role in ensuring accuracy during protein translation, a new look at the trimeric G-protein cycle, the molecular function of ARF in vesicle coating, the emerging role of the dynamin family in vesicle transfer, GTPases which activate GTPases during nascent protein translocation, and the many roles of ras-related proteins in growth, cytoskeletal polymerization, and vesicle transfer. 80 chapters contain much previously unpublished data and, at the rate the extended family of GTPases is growing, it is unlikely that it will again sit for a group portrait such as this. Thus, this could well become the standard reference work.