ENO1 (alpha-enolase) is one of three enolase isoenzymes found in mammals. The alpha (ENO1), gamma (ENO2) and beta (ENO3) subunits form hetero- and homodimers that serve as glycolitic enzymes. ENO1 catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate. It also functions as a structural lens protein (tau-crystallin) in the monomeric form. The shorter isoform of ENO1 has been shown to bind to the c-myc promoter and functions as a tumor suppressor. It has also been identified as an autoantigen in Hashimoto encephalopathy. ENO1 is often overexpressed in cancer, including breast, lung, thyroid, pancreatic, prostate, and hepatocellular cancers as well as neuroendocrine tumors and neuroblastomas. While ENO1 is present in nearly all tissues, the dimer of ENO1 and ENO2 is specifically expressed in microglia, astrocytes and oligodendrocytes in the brain. This dimer is known as NSE, Neuron Specific Enolase, and it is thought to be involved in the regulation of neuronal differentiation, growth, and survival. NSE is considered a useful marker for neuronal damage, as higher levels of NSE correlate with degree of injury and with poor patient prognosis in neurodegenerative diseases and brain injury. References: J Bio Chemi. 275 (8): 5958–65, PMID: 10681589; Experimental Cell Research. 335 (2): 216–23, PMID: 26024773; Molecular Cancer. 13: 65,PMID: 24650096; Brain Sci. 2018 Feb; 8(2): 33, PMID: 29463007; Neurol Res. 1998 Jul; 20(5):418-20, PMID: 9664588;