{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Caldesmon 1, also known as CALD1, is a human gene. Caldesmon is a calmodulin-binding protein. Like Calponin, Caldesmon tonically inhibits the ATPase activity of myosin in smooth muscle. This gene encodes a Calmodulin and actin-binding protein that play an essential role in the regulation of smooth muscle and nonmuscle contraction."}]},{"type":"paragraph","children":[{"type":"text","value":"Two closely-related variants of human Caldesmon have been identifi ed. The h-Caldesmon variant (120–150 kD) is predominantly expressed in smooth muscle, whereas I-Caldesmon (70–80 kD) is found in non-muscle tissue and cells. Neither of the two variants has been detected in skeletal muscle. Anti-Caldesmon recognizes\n only the h-Caldesmon variant. Anti-Caldesmon antibody labels smooth muscle and tumors of smooth muscle, myofibroblastic, and myoepithelial differentiation. Anti-Caldesmon has also been used to differentiate Epithelioid Mesothelioma from Serous Papillary Carcinoma of the ovary."}]}]}