Cell motility and invasion play an essential role in a wide range of biological functions, including many stages of development, wound healing, and immune function. Deregulated motile behavior is believed to contribute to pathological processes such as metastasis, tumor angiogenesis, and atherosclerosis (1 –3 ). Rho family members control a multitude of functions that have been implicated in the regulation of cell migration. Most notable among these are the organization and dynamics of the actin cytoskeleton, intercellular and cell-substrate adhesion, vesicle trafficking, and lipid metabolism (4 ). Recently, Rac has been shown to stimulate the transcription of collagenase-1, a metalloproteinase involved in the remodeling of extracellular matrix (5 ).
