Specificity: This antibody recognizes the a-smooth muscle form of actin. It shows no cross reaction with actin from fibroblasts (b- and g-cytoplasmic), striated muscle (a-sarcometric), and myocardium (a-myocardial). Its epitope is composed of the acetyl group and the first 4 amino acids on the N-terminal end of the peptidic chain of a-smooth actin. ScyTek's 1A4 stains smooth muscle cells in vessel walls, gut wall, and myometrium. Myoepithelial cells in breast and salivary gland are also stained as they also contain this actin.