In order to study local Gal-9 responses in further detail, we focused on the possible impact of Gal-9 on CD34−PDPN+THY1+-expressing FLSs, since these cells have emerged as a currently untargeted proinflammatory cellular subset that is locally upregulated in the sublining layer of the RA synovial membrane [13,14,37]. Here, LGALS9 is linked to rheumatoid arthritis.