ENO2 and neoplasm: Previous studies showed that serum tumor markers, such as carcinoembryonic antigen (CEA), neuron‐specific enolase (NSE), carbohydrate antigen (CA) 19‐9, CA242, and cytokeratin fragment antigen 21‐1 (CYFRA21‐1), expressed in normal cells are abundantly synthesized and secreted in tumor cells.13