PFKFB3 and PFKFB4 coordinate glycolysis and the PPP in cancer cells. PFKFB3 has the highest kinase:phosphatase ratio (710:1), whereas PFKFB4 has more phosphatase activity within a kinase:phosphatase ratio of 4.6:1. Both PFKFB3 and PFKFB4 are hypoxia inducible and contribute to hypoxia-induced glycolysis; however, their functions and biochemical properties are distinct. PFKFB3 strongly increases F-2,6-BP levels and promotes glucose utilization through glycolysis, but reduces glucose entry into the PPP. In contrast, PFKFB4 redirects more glucose through the PPP to produce NAPDH and ribose 5-phosphate, supporting ROS detoxification and lipid and nucleotide synthesis. Co-expression of PFKFB3 and PFKFB4 fine-tunes glucose metabolism in cancer cells, ensuring continued energy supply and redox homeostasis.