Cdc42, Rac1, and their effector IQGAP1 as molecular switches for cadherin-mediated cell-cell adhesion

Cell-cell adhesion is a dynamic process in various cellular and development al situations. Cadherins, well-known Ca2+-dependent adhesion molecules, are thought to play a major role in the regulation of cell-cell adhesion. Howe ver, the molecular mechanism underlying the rearrangement of cadherin-media ted cell-cell adhesion is largely unknown. Cdc42 and Rad, belonging to the Rho small GTPase family, have recently been shown to be involved in the reg ulation of cell-cell adhesion. In addition, IQGAP1, an effector for Cdc42 a nd Rad, has been shown to regulate the cadherin function through interactio n with beta-catenin, a molecule associated with cadherin. In this review, w e will summarize the mode of action of Cdc42 and Rad as well as IQGAP1 as m olecular switches for the cadherin function, and then discuss physiological processes in which the Cdc42/Rac1/IQGAP1 system may be involved. (C) 1999 Academic Press.