SMA

Formalin-fixed, paraffin embedded tissue block or cell block, or 1 unstained charged slide for each test requested plus 3-4 additional unstained slides cut at 4 microns. Adequate space on each slide for control tissue is required.

Actin, a microfilament of the cytoskeleton, consists of six isoforms, which include different a isoforms specific for muscle tissues, i.e., skeletal muscle a, cardiac a, and smooth muscle a. 1A4 reacts with a smooth muscle actin, and identifies tumors with smooth muscle immunophenotype (leiomyoma and leiomyosarcoma) and tumors with myofibroblastic differentiation (the latter with a "tram tract" staining pattern).