HK2 and rheumatoid arthritis: However, both key glycolysis rate-limiting enzymes, hexokinase-II (HK-II), phosphofructokinase-1 (PFK-1), and pyruvate kinase M2 (PKM2), as well as indirect rate-limiting enzymes, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), are thought to participate in the pathogenesis of RA.