Umar et al. found that Penta-o-galloyl-beta-d-Glucose (PGG) could inhibit O-GlcNAcylation of transforming growth factor beta-activated kinase 1-binding protein 1 (TAB1) and reduce TGF-β-activated kinase 1 (TAK1) activation in IL-1β-stimulated human RA synovial fibroblasts (RASFs). Here, TAB1 is linked to rheumatoid arthritis.