LGALS9 and rheumatoid arthritis: Gal-9 modulation of RA via the regulation of synovial fibroblast activity/viability has been shown to be complex, with endogenous Gal-9 protecting synovial fibroblasts against apoptosis (48), while exogenous Gal-9 has been shown to induce apoptosis in fibroblast-like synoviocytes in RA patients (21).