NSE, also named as ENO2, belongs to the enolase family. Enolases are cytoplasmic glycolytic enzymes that may be involved in differentiation. The enolase has three isoenzymes, alpha, beta and gamma. The alpha form is expressed in most tissues, whereas the beta form is expressed in muscle tissue. The gamma enolase (ENO2), a homodimer, is primarily localized in neurons and neuroendocrine cells and is a cancer diagnostic marker for brain tumors (PMID:7520111). ENO2 plays a role in the glycolysis-related energy pathway and might be involved in higher metabolic activity during the day than at night, at least in part.