Tyrosine phosphorylation in the action of neuropeptides and growth factors.

The non-receptor tyrosine kinase p125FAK and the adaptor proteins paxillin and p130CAS are implicated in signal transduction at the focal adhesion plaques. An increase in the tyrosine phosphorylation of p125FAK, paxillin and p130CAS has been identified as an early signal in response to integrin engagement, mitogenic neuropeptides, bioactive lipids and growth factors. Agonist-mediated induction of tyrosine phosphorylation of focal adhesion proteins occurs through a PKC and Ca(2+)-independent pathway that is critically dependent on the integrity of the actin cytoskeleton and on functional Rho. The coordinate tyrosine phosphorylation of p125FAK, paxillin and p130CAS plays a role in cell locomotion, DNA synthesis and apoptosis.