Enolase is a glycolytic enzyme catalyzing the reaction pathway between 2 phospho glycerate and phosphoenol pyruvate. In mammals, enolase molecules are dimers composed of three distinct subunits (alpha, beta and gamma). The alpha subunit is expressed in most tissues and the beta subunit only in muscle. The gamma subunit is expressed primarily in neurons, in normal and in neoplastic neuroendocrine cells. NSE (neuron specific enolase) is found in elevated concentrations in plasma in certain neoplasias. These include pediatric neuroblastoma and small cell lung cancer. Coexpression of NSE and chromogranin A is common in neuroendocrine neoplasms.