PKM and neoplasm: Likewise, in colon cancer and glioma cells, it was found that CD44 regulates the phosphorylation of pyruvate kinase M2 (PKM2), a key enzyme in the glycolysis of tumor cells, and thereby increases glycolytic metabolism, promoting an increase in glucose uptake and glutathione production to decrease the generation of reactive oxygen species (ROS) in hypoxic cells (46).