Lactate dehydrogenase (LDH) catalyzes the conversion of the glycolysis productpyruvate to lactate, accompanied by the oxidation of NADH to NAD+(Fig. 1).In a healthy human organism, LDH isoform A (LDH-A) is found primarilyin skeletal muscles; isoform B – in heart muscle; and C – in testes[1, 2].In many tumor cells, activation of pyruvate conversion by LDH and reduced pyruvateoxidation in the mitochondria is observed. This evidence concerns the gene LDHA and neoplasm.