57 reported that, although melanoma patients showed high levels of serum LDH, monocarboxylate transporters MCT4, (the principal transporter for lactate efflux69 and a downstream effector of hypoxia-inducible factor (HIF)-1a,70) indicating that the melanoma cells predominantly used glycolysis for energy production, the serum lactate levels remained constant. The gene discussed is HIF1A; the disease is melanoma.