PHGDH and neoplasm: Interestingly, when the concentration of glucose or glutamine is low (nutrients deprivation), tumor cells induce c-Myc to promote their survival via regulation of metabolic enzyme expression in the serine synthesis pathway, including phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), phosphoserine phosphatase (PSPH), activating the de novo serine synthesis and preserving redox homeostasis [31].