Figure 3.

FRS2α is essential for Gab1 recruitment and activation of PI-3 kinase. (A) Fibroblasts were stimulated with FGF1 and heparin. Cell lysates were immunoprecipitated with anti-Gab1 antibodies followed by immunoblotting with the indicated antibodies. (B) FRS2α-deficient fibroblasts were infected with expression vector for wild-type or FRS2α mutants or with vector alone. Following FGF1 stimulation, cell lysates were subjected to immunoprecipitation with anti-FRS2 or anti-Gab1 antibodies, followed by immunoblotting with antibodies as indicated. (C) PI3-kinase assay was performed on Gab1 immunoprecipitates derived from wild-type or mutant fibroblasts (Left) or from mutant fibroblasts transfected with expression vector encoding for FRS2α or vector alone (Right).