<prompt> The metabolite that is regarded as the dead end in glycolysisPyruvateLactate2,3-bisphosphoglycerate3-phosphoglycerate  <response>: Lactate is always the end product of glycolysis, lactate has been considered a dead -end waste product. Congruently, the end product of glycolysis has been viewed dichotomously: pyruvate in the presence of adequate oxygenation, La- in the absence of adequate oxygenation. In contrast, given the near-equilibrium nature of the lactate dehydrogenase LDH reaction and that LDH has a much higher activity than the putative regulatory enzymes of the glycolytic and oxidative pathways, we contend that La- is always the end product of glycolysis. Cellular La- accumulation, as opposed to flux, is dependent on 1 the rate of glycolysis, 2 oxidative enzyme activity, 3 cellular O2 level, and 4 the net rate of La- transpo into influx or out of efflux the cell. For intracellular metabolism, we reintroduce the Cytosol-to-Mitochondria Lactate Shuttle. Our proposition, analogous to the phosphocreatine shuttle, purpos that pyruvate, NAD, NADH, and La- are held uniformly near equilibrium throughout the cell cytosol due to the high activity of LDH. La- is always the end product of glycolysis and represents the primary diffusing species capable of spatially linking glycolysis to oxidative phosphorylation. 