Smooth muscle gamma actin (ACTG2) is a protein that is a component of the cytoskeleton in smooth muscle and is involved in cell motility. Mutations of the ACTG2 gene result in visceral myopathy, a rare form of myopathic pseudo-obstruction. ACTG2 is localized to the cytoplasm of myoepithelial cells, predominantly in enteric tissues. Aberrant expression has been reported in several types of cancer such as colorectal, breast, laryngeal, and small intestinal neuroendocrine tumors, which may affect chemotherapy sensitivity. Staining is used to identify smooth muscle cells in normal tissue and in disease. References: Mol Cell Biol. 1991;11(6):3296-3306. PMID: 1710027; PLoS Genet. 2014;10(3):e1004258. doi: 10.1371/journal.pgen.1004258; BMC Endocr Disord. 2016;16:19. doi: 10.1186/s12902-016-0100-3; Cancer Biother Radiopharm. 2013;28(7): 552-558. doi: 10.1089/cbr.2012.1431; Acta Oncol. 2007;46(5):651-658. doi: 10.1080/02841860601156157; Int J Clin Exp Pathol. 2013;6(7):1351-1361. PMID: 23826416