N-Terminal decapeptide of alpha smooth muscle isoform of actin was used as the immunogen for the Smooth Muscle Actin antibody.
Actin is a major component of the cytoskeleton and is present in most cell types. It is highly specific to actin from smooth muscles. This MAb does not stain cardiac or skeletal muscle, however, it does stain myofibroblasts and myoepithelial cells. This antibody could be used together with anti-muscle specific actin and myogenin in making a diagnosis of smooth muscle and skeletal muscle tumors. In most cases of rhabdomyosarcoma, this antibody yields negative results whereas anti-muscle specific actin and myogenin are positive. Leiomyosarcomas are positive only with anti-muscle specific actin and anti-smooth muscle actin and are negative with anti-myogenin.
