CD34 and rheumatoid arthritis: The results revealed that the 3,3′‐diaminobenzidine (DAB) staining intensity of CD68 and CD34 in the synovial tissues of RA patients was significantly higher than that in those of osteoarthritis (OA) patients (Figure S2A, Supporting Information), whereas the expression levels of these two markers were partially consistent in the RA sample (Figure S2B, Supporting Information).