Tumor vascular endothelial cells, like cancer cells, are dependent on the glycolytic regulator phosphofrucokinase-2/fructose-2, 6-bisphophatase 3 (PFKFB3) [32], and tumor vascular endothelial cells are resistant to the acidic environment of cancer tissue due to increased expression of carbonic anhydrase II (CAII) [33, 34]. The gene discussed is CA2; the disease is cancer.