PHGDH and breast cancer: In this section, we discuss the implications of key factors of glucose metabolism, including hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), pyruvate dehydrogenase kinase (PDK), 3-phosphoglycerate dehydrogenase (PHGDH), and lactate dehydrogenase (LDH), in breast cancer progression and drug resistance (Table 1).