Moreover, CXCL13 production by Sox4-expressing CD4+ T cells not only in TGF-β-positive, IL-2-limiting conditions but also in Th1-polarizing conditions might imply the possible involvement of Sox4 in ELS formation via CXCL13 in Th1-dominant conditions, such as tumor microenvironments, in addition to the locally inflamed sites of RA. Here, TGFB1 is linked to rheumatoid arthritis.