The identification of increased 2-hydroxyglutaric acid (2HG) (Fig. S3), which is converted from glutamine-derived α-KG in cancer cells having deficient activity of isocitrate dehydrogenase (IDH) 1 or 2 due to mutation and in mammalian cells under hypoxia (39, –, 43), also suggests a connection of glutamine catabolism to the TCA cycle during M1-like polarization. The gene discussed is IDH3A; the disease is cancer.