A few previous studies showed a similar observation where the changes in lactate production were not linked to the changes in the levels of LDH, but with other metabolic enzyme, such as pyruvate kinase PKM2 [37] or pyruvate dehydrogenase [38,39], in the context of other diseases, including brain tumor, neuroinflammation, and traumatic brain injury. The gene discussed is PKM; the disease is brain neoplasm.