6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 1 is an enzyme that in humans is encoded by the PFKFB1 gene. The enzyme forms a homodimer that catalyzes both the synthesis and degradation of fructose-2,6-biphosphate using independent catalytic domains. It belongs to the phosphoglycerate mutase family. Fructose-2,6-biphosphate is an activator of the glycolysis pathway and an inhibitor of the gluconeogenesis pathway. Consequently, regulating fructose-2,6-biphosphate levels through the activity of this enzyme is thought to regulate glucose homeostasis.