We found similar, albeit less dramatic effects of glutamine deprivation on cell proliferation of H661 and H838 cells (Supplementary Fig. S8C and S8E, respectively), and PPAT and PAICS expression (Supplementary Fig. S8D and S8F), suggesting one of several critical roles of glutamine is in activating de novo purine biosynthesis pathway genes and altering cancer cell metabolism. The gene discussed is PPAT; the disease is cancer.