The transgelin family is a group of proteins that belong to 22kd actin-related corpnin superfamily. Of all three isoforms,transgelin 1 is the best characterized. Transgelin 1,also known as SM22alpha,is a specific marker for differentiated smooth muscle cells. Transgelin 2,also known as SM22 beta,is expressed by both smooth muscle and non-smooth muscle cells in a temporally and spatially regulated pattern. Trangenlin 3,also known as NP25,is only found in highly differentiated neuronal cells.