 Integrins bind extracellularly to fibronectin, laminin, or other ECM components, and intracellularly to microfilament-binding proteins α-actinin and talin to link the cytoskeleton with the outside.Integrins also serve as receptors to trigger signal transduction cascades when binding to the ECM.A well-studied example of morphogenesis that involves ECM is mammary gland ductal branching.