ACTA2 - Smooth muscle marker

The ACTA2 gene encodes for alpha smooth muscle actin (SMA, ASMA), a member of the actin family of proteins. SMA is expressed in smooth muscle cells, myofibroblasts and myoepithelial cells. In clinical immunohistochemistry, SMA antibodies can be useful to visualize smooth muscle cells in vascular walls, gut tissue, uterus etc. and to detect myoepithelial cells in breast for distinguishing invasive breast cancer from benign sclerosing lesions and ductal carcinoma in situ (DCIS). Alpha smooth muscle actin antibodies are also used in research to identify cancer associated fibroblasts (CAF) in the stroma that surrounds cancer cells.