The Met tyrosine kinase–the HGF receptor–induces cell transformation and metastasis when constitutively activated. Met signaling is mediated by phosphorylation of two carboxy-terminal tyrosines which act as docking sites for a number of SH2-containing molecules. These include Grb2 and p85 which couple the receptor, respectively, with Ras and PI 3-kinase. We previously showed that a Met mutant designed to obtain preferential coupling with Grb2 (Met 2xGrb2) is permissive for motility, increases transformation, but–surprisingly–is impaired in causing invasion and metastasis. In this work we used Met mutants optimized for binding either p85 alone (Met 2xPI3K) or p85 and Grb2 (Met P13K/Grb2) to evaluate the relative importance of Ras and PI 3-kinase as downstream effectors of Met. Met 2xPI3K was competent in eliciting motility, but not transformation, invasion, or metastasis. Conversely, Met P13K/Grb2 induced motility, transformation, invasion and metastasis as efficiently as wild type Met. Furthermore, the expression of constitutively active PI 3-kinase in cells transformed by the Met 2xGrb2 mutant, fully rescued their ability to invade and metastasize. These data point to a central role for PI 3-kinase in Met-mediated invasiveness, and indicate that simultaneous activation of Ras and PI 3-kinase is required to unleash the Met metastatic potential.