HK2 and rheumatoid arthritis: Stimulation of RA FLS with CoCl2, which mimics hypoxia, and PDGF for 60 min triggered HK2 mitochondrial binding but not its HK activity (Supplementary Figure 1A), as detected by an overlap of HK2 in green and ATP5b (a marker of mitochondria) in red by immunofluorescent confocal microscopy (Figures 1A, B).