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Integrin-mediated cell adhesion causes activa-tion of MAP kinases and increased tyrosine phosphoryla-tion of focal adhesion kinase (FAK). Autophosphory-lation of FAK leads to the binding of SH2-domain proteins including Src-family kinases and the Grb2–Sos complex. Since Grb2–Sos is a key regulator of the Ras signal transduction pathway, one plausible hypothesis has been that integrin-mediated tyrosine phosphoryla-tion of FAK leads to activation of the Ras cascade and ultimately to mitogen activated protein (MAP) kinase activation. Thus, in this scenario FAK would serve as an upstream regulator of MAP kinase activity. How-ever, in this report we present several lines of evidence showing that integrin-mediated MAP kinase activity in fibroblasts is independent of FAK. First, a