The MCT1-mediated efflux of lactates from highly glycolytic tumor/stromal cells ensures the progression of glycolysis and prevents intracellular acidification (extracellular lactates provide not only a respiratory fuel for oxidative cells, but also contribute to an acidic tumor microenvironment promoting migration, angiogenesis, and immunosuppression). The gene discussed is SLC16A1; the disease is neoplasm.