HK2 and neoplasm: In the past decade, many enzymes involved in glucose and lipid metabolisms have become the focus of research, including pyruvate kinase M2 (PKM2) [6], hexokinase-2 (HK-2) [7], and isocitrate dehydrogenase (IDH1/2) [8], and all of them have been reported as new targets of tumor-targeted therapy.