Small GTPases, adhesion, cell cycle control and proliferation

In many cells, proliferation is under the coordinated control of growth fac tors and the extracellular matrix (ECM). Autocriny and anchorage-independen t growth are observed in many transformed cells where this balance is often altered. The outside-in and inside-out exchanges are mediated by integrins , acting as molecular bridges between the ECM and the cytoskeleton. Integri ns, as the major receptors for components of the ECM, are important not onl y for the physical aspects of cell adhesion, but also for two key aspects o f cell fate: cell cycle progression, and apoptosis. The latter aspect will not be covered in the present analysis, which will rather focus on the data accumulated on Ras and Ras-related small GTPases such as Rho, Rac and Cdc4 2. (C) 2000 Editions scientifiques et medicales Elsevier SAS.