PFKFB4 and prostate carcinoma: Interestingly, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 (PFKFB4), an isoform of PFK2, was required for the survival of prostate cancer cells but not benign prostate epithelial cells.7 This is significant because this isoform has a greater phosphatase activity relative to its kinase activity and therefore favors the breakdown of fructose 2,6-bisphosphate, an allosteric activator of PFK1.