Actin, Muscle Specific (MSA)

MSA (muscle-specific actin), a microfilament protein with contractile capacity, is a major component of the highly conserved cytoskeleton. MSA is widely expressed in almost all muscle cells, skeletal muscle, myocardium, smooth muscle cells, and muscle-differentiated tumors such as leiomyoma and rhabdomyosarcoma. However, MSA is not expressed in endothelial cells, connective tissues, carcinomas, melanomas, lymphomas and most non-muscle sarcomas.