Fig. 3

Metabolic alterations involved in activated cells. Activated cells take up large amounts of glucose and glutamine and divert them to the pentose phosphate pathway (PPP) and lipid biosynthesis, respectively. Coupled to increased uptake of glycine, serine, and branched chain amino acids (leucine, isoleucine, and valine), which are required for protein synthesis, this generates sufficient building blocks (nucleic acids, proteins, and membranes) for proliferation. The increased generation of reactive oxygen species requires appropriate levels of antioxidants, most of which originate from the PPP. These metabolic changes generate bioactive metabolites that are secreted, and that also contribute to cell activation. Abbreviations: 3-PG 3-phosphoglycerate, A-KG α-ketoglutarate, CoA coenzyme A, G6P glucose-6-phosphate, LPA lysophosphatidic acid, L-AA L-amino acids, R5P ribose-5-phosphate, S1P sphingosine-1-phosphate, PPP pentose phosphate pathway