Myofibroblast-Mediated Contraction.

Myofibroblast-mediated contraction is viewed as a cycle of four steps. The first step is stimulation of myofibroblasts by lysophospholipids leading to the activation of G proteins and ending with contraction of the actin-myosin complex. The next step is the transmission of the intracellular contractile force at the focal adhesions of myofibroblasts; a step that involves talin, vinculin, paxillin, Hic-5, and the integrin receptors. In the third step, fibronectin will act as the extracellular link between the integrin receptors and the extracellular collagen. Finally, "sensing" tension and the maintenance of myofibroblast activity represent the fourth step. The clinical relevance of each step is then discussed in the form of modalities to prevent excessive scarring/fibrosis.