Transgelin (SM22-alpha) is a calponin which is expressed exclusivelyin smooth muscle-containing tissues of adult animals and is one of the earliestmarkers of differentiated smooth muscle cells [<cite idref="PUB00000982"/>, <cite idref="PUB00002906"/>]. It is the product of a single gene that is conserved in yeast, Drosophila, molluscs and humans [<cite idref="PUB00000982"/>], and is highly similar to several other proteins of unknown function (including mouse p27 and human WS3-10). The smaller domains of similarity shared between transgelin and other proteins, such as rat NP25, chicken calponins alpha and beta, and Drosophila mp20, suggest that these proteins may be classified as members of a new transgelin multigene family [<cite idref="PUB00000982"/>]. Transgelin (SM22-alpha)