Fig. 7. Model of Dock180 regulation. (A,B) Following integrin stimulation by their ligands (including fibronectin), tyrosine kinases are activated and phosphorylate several components of focal adhesion such as p130Cas, and both Crk and Dock180 are recruited from the cytoplasm. (C) Recruited Dock180 is known to activate Rac, and we speculate that recruited Dock180 is ubiquitylated near the plasma membrane by an ubiquitin ligase. (D) Furthermore, ubiquitylated Dock180 might be removed from the complex comprising Crk and p130Cas, and is degraded by the proteasome.