Book excerpt: This second of two volumes discusses subfamily proteins which function in molecular and vesicular transport mechanisms inside the cell. In this volume the focus lies on the Rab, Ran and Arf subfamily members. As in Volume 1, the book is written by international renowned scientists in the field of small G-proteins. In elaborate reviews, biochemistry, structure, function and G-protein - effector interactions are described. Together with Volume 1 this book provides an comprehensive state-of-the-art work on small G-proteins (GTPases). It is written for Graduates and Professors in Biochemistry and Cell Biology interested in the mechanism and function of small G-proteins but are extremely valuable for those who want to move into the field.