ABSTRACT
Many cells in culture adhere to the underlying substratum via specialized regions, known as focal adhesions. These are areas where integrins, receptors for extracellular matrix (ECM) proteins, are clustered and adhesion is made to ECM components adsorbed to the surface on which the cells are growing. The assembly of focal adhesions and their associated bundles of actin filaments is regulated by the GTPase Rho A. This chapter describes methods for studying RhoA by microinjection, and describes assays for the contractility of cultured cells. Contractility in nonmuscle cells is generated by the interaction of myosin II with actin filaments. Phosphorylation of the myosin light chain occurs at multiple sites and is catalyzed by several distinct protein kinases.
