G6PD and rheumatoid arthritis: As some studies have reported that RA T cells are characterized by the increased availability of the pentose phosphate pathway (24), we next examined two key enzymes that regulate the pentose phosphate pathway, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and glucose-6-phosphate dehydrogenase (G6PD).