Actin,Muscle Specific

Muscle specific actin (MSA) is a highly conserved cytoskeletal protein that widely exists in smooth muscle cells and striated muscle cells. It has various functions such as maintaining cell morphology, mediating cell migration, and participating in muscle contraction. In clinical practice, MSA is a diagnostic indicator for smooth muscle derived tumors, including angioleiomyoma, gastrointestinal leiomyoma, small intestinal leiomyosarcoma, etc. Meanwhile, MSA is positively expressed in rhabdomyosarcoma (RMS), and its expression level is up-regulated with increasing differentiation of RMS. Therefore, MSA can be used as a reference indicator for evaluating tumor recurrence and patient prognosis. However, MSA has low specificity, so it is often used in combination with SMA, Calponin, Desmin, Vimentin, and other antibodies. In addition, some scholars found that MSA can be expressed in salivary gland adenoid cystic carcinoma (ACC) but not in breast ACC, which provides a new research direction for ACC pathogenesis.