Cell adhesion integrins regulation

Fak (focal adhesion kinase) is expressed in most tissues and is evolutionary conserved across species. It is activated by integrin clustering and by stimulation of several G protein-coupled recqrtors and RTKs. Fak is associated with focal adhesions and regulates cell spreading and migration. The kinase is essential for embryonic development since the homozygote Fak knockout is embryonic lethal. Pyk2 (proline-rich tyrosine kinase 2), the second member of the Fak kinase family has a more restricted expression pattern (primarily neuronal and hematopoietic cells) and does not localize to focal adhesions. 

THE THREE-DIMENSIONAL STRUCTURE OF INTEGRINS AND THEIR LIGANDS, AND CONFORMATIONAL REGULATION OF CELL ADHESION... 

The Rho family of small GTP-binding proteins functions to regulate the assembly of distinct actin structures in cells Rho regulates stress fiber assembly, Rac regulates lamellipodia protrusion and Cdc42 stimulates protrusion of the plasma membrane to form filopodia (Ridley and Hall, 1992 Ridley et at., 1992 Nobes and Hall, 1995 Kozma et at., 1995). All three regulate attachment of cells to the extracellular matrix via adhesive integrin structures (Nobes and Hall, 1995). 

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