S100A1 (s100 calcium-binding protein A1) is an 100 family protein found in abundance in the brain and in cardiac and skeletal muscle. It is implicated in the pathogenesis of a number of neurological diseases such as Alzheimer’s disease. It is also a marker for cardiotoxicity in breast and prostate cancers and a therapeutic target in cardiovascular disease. Animal studies have shown that ;oss of S100A1 leads to increased blood pressure values while overexpression leads to better contractile performance and superior survival from myocardial infarction. In immunohistochemistry, S100A1 has cytoplasmic and nuclear positivity in the central nervous system, skeletal and heart muscle, melanocytes, salivary glands, kidney, thyroid and a few other tissues. References: J Cardiovasc Transl Res. 2010 Oct; 3(5): 525–537, PMID: 20645037; PLoS One. 2015 Dec 18;10(12):e0145418, PMID: 26682543; Curr Chem Biol. 2009 May 1;3(2):138-145, PMID: 19890475; Biochemistry. 31 (42): 10258–64, PMID: 1384693;