GYS1 and rheumatoid arthritis: Interestingly, treatment with the AMPK agonist AICAR or inhibitor Compound C did not affect GYS1 phosphorylation and expression, intracellular glycogen levels at different time point (Figures 3F,G), suggesting that the AMPK pathway does not participate in GYS1-mediated glycogen synthesis in RA FLSs.