Figure 9.

Summary diagram: integrin-mediated cytoskeletal assembly and cell migration are both controlled by the physical status of the ECM. Binding of the α₅β₁ integrin to its ligand fibronectin results in the formation of fibrillar adhesions that contain tensin as a major cytoskeletal component and that are associated with actin filaments. Matrix immobilization prevents matrix reorganization and formation of fibrillar adhesions. When the same integrin binds to an immobilized fibronectin ligand, it forms typical, highly phosphorylated FCs that associate with the termini of actin stress fibers, accompanied by reduction of cell migration rates. The latter FC type of adhesion depends on actomyosin-mediated contractility that can be inhibited by H-7 or ML-7. In contrast, fibrillar adhesions are not disrupted by these inhibitors.