Role of focal adhesion kinase in MAP kinase activation by insulin-like growth factor-I or insulin

Integrin-induced focal adhesion kinase (FAK) phosphorylation as well as ins ulin-like growth factor-I (IGF-I) and insulin activate MAP kinase, Since IG F-I or insulin have been suggested to affect FAK phosphorylation, we analyz ed the role of FAK in IGF-I- or insulin-induced MAP kinase activation. Alth ough MAP kinase was stimulated by IGF-I or insulin, FAR tyrosine- phosphory lation remained unchanged in fibroblasts expressing normal or transiently e levated levels of IGF-I and insulin receptors, Further analysis in FAK defi cient fibroblasts suggested that FAK impedes MAP kinase activation by IGF-I or insulin. (C) 1999 Federation of European Biochemical Societies.