CD68 and rheumatoid arthritis: The increment of miR-155 has been reported in different cell types or tissues of RA, such as synovial tissue (51–53), CD68+ synovial macrophages (50, 52–54), RA synovial fluids (RASFs) (51, 55), synovial fluid CD14+ cells (51, 54), PBMCs (56–58), and whole blood of RA patients (58).