– VB-124 is a potent and selective MCT4 inhibitor. VB124 might redirect glycolytic carbon flux into mitochondrial pyruvate oxidation. VB 124 bolcks lactate import (IC50=8.6nM), and export (IC50=19nM) in MDA-MB-231 cells that are engineers to express MCT4 as the only major plasma membrane lactate transporter.