Cell migration is critical to morphogenesis and correct patterning of the mouse embryo. Cells are specified in a region of the embryo then, in response to chemical signals, they migrate extensively before they reach their final location. Although the molecular mechanisms of cell migration in single cells have been extensively studied over the past decades, little is known about the identity of the signals and how they are transduced to the cytoskeletal or adhesive cell systems to elicit the migratory behavior of the cells during the morphogenesis of the embryo. We hypothesize that Fgf receptors control mesoderm migration by activation of Ect2, which activates Rac1, which in turn activates the WAVE complex to promote migration. We are studying the exact mechanisms that link signaling to cell migration of mesoderm cells in the gastrulating mouse embryo. Our findings will have important implications for the functions of Fgfr, Ect2 and Rac1 signaling in the pathogenesis of diverse tumor types.