PSAT1 and glioblastoma: Notably, glutamine-deprived treatment of U87 and T98 GBM cells resulted in the upregulation of phosphoserine aminotransferase 1 (PSAT1), serine hydroxymethyl transferase 2 (SHMT2), methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), and methylenetetrahydrofolate dehydrogenase 1L (MTHFD1L) (Fig. 3b), suggesting a potential metabolic flux from serine to glycine for the high rates of one-carbon metabolism in the mitochondrion.