Crosstalk can even be observed across membranes. Membrane interactions with the extracellular matrix (ECM) and with neighboring cells can trigger a variety of responses within the cell. However, the topography and mechanical properties of the ECM also come to play an important role in powerful, complex crosstalk with the cells growing on or inside the matrix. For example, integrin-mediated cytoskeleton assembly and even cell motility are affected by the physical state of the ECM. Binding of the α5β1 integrin to its ligand (fibronectin) activates the formation of fibrillar adhesions and actin filaments. Yet, if the ECM is immobilized, matrix reorganization of this kind and formation of fibrillar adhesions is inhibited. In turn, binding of the same integrin (α5β1) to an immobilized fibronectin ligand is seen to form highly phosphorylated focal contacts/focal adhesion (cells involved in matrix adhesion) within the membrane and reduces cell migration rates In another example of crosstalk, this change in the composition of focal contacts in the cytoskeleton can be inhibited by members of yet another pathway: inhibitors of myosin light-chain kinases or Rho kinases, H-7 or ML-7, which reduce cell contractility and consequently motility. (see figure 2).