Aldolase (fructose bisphosphate aldolase), a glycolytic enzyme, catalyzes the conversion of fructose 1, 6-bisphosphate to 3-phosphoglyceraldehyde. This ubiquitous enzyme is present as three different isozymes: aldolase A, aldolase B, and aldolase C. Research studies suggest that aldolase A expression potentially differentiates between nonneoplastic liver diseases and hepatocarcinoma. Aldolase A is found in the developing embryo and is produced in even greater amounts in adult muscle. Aldolase A expression is repressed in adult liver, kidney, and intestine and similar to aldolase C levels in brain and other nervous tissue.