Correlated to the evidence of an O-GlcNAcylation-mediated increase of the cancer cell anabolism, some enzymes of the serine biosynthesis pathway, d-3-phosphoglycerate dehydrogenase (PHGDH) and phosphoserine aminotransferase 1 (PSAT1), of the glycine cleavage system, glycine decarboxylase (GLDC), and of thymidine synthesis pathway, thymidine kinase (TK), have also been found modified by O-GlcNAcylation [96,98,108,109]. The gene discussed is PHGDH; the disease is cancer.