The pentose phosphate pathway, not glycolysis, is essential for Kras-induced growth under aerobic conditions. (A) Analysis of soft agar colonies of HCT116 cells, in media containing combinations of 20 mM glucose, 20 mM galactose, 4 mM glutamine, and 1 mM sodium pyruvate. (B) Ratio between oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) of HCT116 cells incubated with 4 mM glutamine plus 20 mM glucose or galactose. Mean ± SE (n = 20). **P < 0.01 (C) Ratio between OCR and ECAR of control and GPI shRNA #1 and #2 in HCT116 cells. Mean ± SE (n = 20). **P < 0.01 (D) Analysis of soft agar colonies of HCT116 expressing control or GPI shRNAs grown under normoxia (21% O2) or hypoxia (3% O2). Bars represent the mean ± SE (n = 16). **P < 0.01.