PFKFB3 and cancer: PFKFB3 is endowed with a much higher kinase/phosphatase activity, compared to the normal enzyme, and allows cancer cells to maintain high glycolytic rates, by producing fructose 2,6-bisphosphate; the latter in turn activates phosphofructokinase activity of the bifunctional PFK1/FBP enzyme making it at the same time insensitive to ATP inhibition.