3-Phosphoglycerate dehydrogenase (PHGDH) is a key enzyme in the serine synthesis pathway, responsible for converting 3-phosphoglycerate to 3-phosphohydroxypyruvate. PHGDH is mainly located in the cytoplasm and is widely expressed in various tissues, particularly at higher levels in rapidly proliferating cells such as cancer cells and embryonic tissues. PHGDH plays an important role in regulating amino acid metabolism, nucleotide synthesis, and antioxidant defense. Gene expression is regulated by various factors, and mutations or abnormal expression are associated with the development of cancer, metabolic disorders, and neurological diseases.