The metabolic enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 4 (PFKFB4), highly expressed in cancer cell lines under hypoxia [92], regulates cellular levels of fructose-2,6-bisphosphate (F2,6BP), an important sugar-phosphate metabolite that stimulates glycolysis by allosteric activation of PFK1. The gene discussed is PFKFB4; the disease is cancer.