FAP and rheumatoid arthritis: Croft et al. [175] classified FAPα+THY1+ immune effector fibroblasts and FAPα+THY1− bone destructive fibroblasts, while Zhang et al. [26] identified THY1(CD90)+HLA-DRAhigh subliming fibroblasts as the potential major source of IL-6 in the synovium of RA patients.