01Glycolysis even with oxygen
In the 1920s Otto Warburg noticed tumors consume huge amounts of glucose and convert it to lactate even when oxygen is plentiful — aerobic glycolysis. This seems wasteful: glycolysis yields 2 ATP per glucose versus ~30 from full oxidation.
The payoff is building material. Rapidly dividing cells need carbon for nucleotides, lipids and amino acids. Glycolytic intermediates feed the pentose phosphate pathway (ribose, NADPH) and serine synthesis.
02Who drives it
AKT boosts glucose transporters; MYC raises glycolytic enzymes and glutamine uptake; HIF-1α (stabilized in low oxygen or by VHL loss) shifts metabolism toward glycolysis. Tumors favor the PKM2 isoform of pyruvate kinase, which slows the last glycolytic step so upstream intermediates pile up for biosynthesis.
Clinically, the glucose hunger is visible: FDG-PET scans use a radioactive glucose analog to light up tumors.