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. Author manuscript; available in PMC: 2015 Jul 1.
Published in final edited form as: Science. 2013 Oct 11;342(6155):1242454. doi: 10.1126/science.1242454

Fig. 2. Metabolic pathways that support cell growth and proliferation.

Fig. 2

Glycolysis and the TCA cycle are two separate yet connected biochemical pathways that function to generate ATP as well as metabolic precursors for biosynthesis. Glucose is broken down to pyruvate by glycolysis (orange); pyruvate can be further oxidized by the TCA cycle in the mitochondrion. Glycolytic intermediates can be used to generate other metabolites required for growth and proliferation. Glucose 6-phosphate and 3PG produced from glycolysis are metabolized in the PPP (green) and the SBP (blue), respectively, providing important precursors for nucleotide biosynthesis. Similarly, acetyl-CoA, generated from glucose-derived citrate in the TCA cycle, can be used for lipid biosynthesis. OAA, produced as part of the TCA cycle, can be used to generate aspartate, another precursor for nucleotide synthesis. An alternate source of carbon for the TCA cycle occurs via glutaminolysis (purple); in this pathway, glutamine is converted to glutamate and then to α-KG, which joins the TCA cycle. Glutamine is also a precursor for amino acid and nucleotide biosynthesis. Key enzymes in these pathways are PHGDH; PKM2; LDHA, lactate dehydrogenase; PDH; GLS, glutaminase; SDH, succinate dehydrogenase; and FH.