['Co-stimulation with lysophosphatidic acid (LPA) and fibronectin (FN) is essential for migration of rat ascites hepatoma MMI cells. We examined the roles of LPA and FN in Rho-FAK pathway to migration.', 'We evaluated the morphology, phagokinetic motility and the status of Rho activation and tyrosine-phosphorylation of FAK after stimulation of MMI or HT-1080 cells with LPA + FN or each alone.', 'On FN-coated dishes without LPA, MM1 cells could not migrate and harbored undetectable levels of activated RhoA. Stimulation with LPA + FN enabled the MM1 cells to migrate and bear active RhoA and sustained tyrosine-phosphorylation of FAK. To the contrary, HT-1080 cells could migrate and harbored a significant amount of active RhoA accompanied by sustained tyrosine-phosphorylation of FAK even without LPA.'] Is sustained tyrosine-phosphorylation of FAK through Rho-dependent adhesion to fibronectin essential for cancer cell migration?