Hexokinase I (HK-I) is a subtype of the hexokinase family. The primary function of HK-I is to regulate the entry of glucose into the glycolytic pathway and generate ATP. It is firmly bound to mitochondria and, in the brain, HK-I catalyzes the phosphorylation of glucose, determining the rate of glycolysis in the brain. HK-I also acts as a coordinating enzyme to prevent an imbalance between glycolysis and mitochondrial oxidative reactions, which could lead to the accumulation of lactic acid. Additionally, in hematopoietic cell lines, HK-I is co-expressed with GLUT1, increasing the level of glucose phosphorylation and the level of cellular nicotinamide adenine dinucleotide phosphate (NADPH), thereby exerting an anti-apoptotic effect.