Key enzymes such as D-3-Phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH) are upregulated in melanoma, enhancing nucleotide synthesis, methylation reactions, and antioxidant defense via glutathione production [68,69]. The gene discussed is PHGDH; the disease is melanoma.