Enolase is an important glycolytic enzyme involved in the interconversion of 2-phosphoglycerate to phosphoenolpyruvate. Mammalian enolase exists as three subunits: enolase-1 (?-enolase), enolase-2 (?-enolase) and enolase-3 (?-enolase) that can form both homo- and heterodimers. Expression of the enolase isoforms differs in a tissue specific manner. Enolase-1 plays a key role in anaerobic metabolism under hypoxic conditions and may act as a cell surface plasminogen receptor during tissue invasion. Abnormal expression of enolase-1 is associated with tumor progression in some cases of breast and lung cancer. Alternatively, an enolase-1 splice variant (MBP-1) binds the c-myc promoter p2 and may function as a tumor suppressor. For this reason enolase-1 is considered as a potential therapeutic target in the treatment of some forms of cancer.