PFKFB4 and rheumatoid arthritis: The largest difference between RA and HC neutrophils was the expression of the gene for 6-Phosphofructo-2-Kinase/Fructose-2,6-Bisphosphatase 3 (PFKFB3) which was significantly higher in RA neutrophils (FDR = 0.01, Fig. 1B).