CD68 and rheumatoid arthritis: In addition, increased colocalization of IGF2BP3 with CD68 (a macrophage marker) was observed, which suggested increased macrophage infiltration was accompanied by increased IGF2BP3 expression in RA synovial tissue (Fig. 1b); and synovial cell (Vimentin was used as a marker of synovial cells) proliferation in RA synovial tissue was accompanied by increased IGF2BP3 expression (Fig. 1c).