{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Calponin binds to actin, tropomyosin, and calmodulin to regulate smooth muscle contraction by tonically inhibiting the ATPase activity of myosin in smooth muscle. There are three calponin isoforms: the basic (CNN1), neutral (CNN), and acidic (CNN3) isoforms, all separate gene products. Calponin 1 is specifically expressed at abundance in smooth muscle cells and plays a role in modulating contractility. Calponin 2 is expressed in both smooth muscle and many types of non-muscle cells, and functions as a regulator of the actin cytoskeleton in fundamental activities such as cell proliferation, migration, adhesion, phagocytosis, angiogenesis, immune responses, and cancer metastasis. Calponin 3 is expressed in smooth muscle and several types of non-muscle cells with demonstrated functions in regulating neuronal plasticity, and cell fusion with a critical role in embryonic development. Anti-calponin is used to identify myoepithelial cells in breast lesions."}]}]}