Research Article Effects of constitutively active GTPases on fibroblast behavior

The GTP-binding proteins RhoA, Cdc42 and Rac1 regulate the organization and turnover of the cy- toskeleton and cell-matrix adhesions, structures bridging cells to their support, and translating forces, external or generated within the cell. To investigate the specific re- quirements of Rho GTPases for biomechanical activities of clonal cell populations, we compared side-by-side sta- ble lines of human fibroblasts expressing constitutively active (CA) RhoA, Cdc42 or Rac1. There was no marked effect of any CA GTPase on cell adhesion to different ex-