TGFB1 and rheumatoid arthritis: Furthermore, pSS SGs biopsy specimens were characterised by an elevated expression of TGF-β1 in the glandular epithelium, and TGF-β1, pSMAD2/3, and SMAD4 proteins were widely expressed in the pSS tissue in patients.11 In RA TGF-β/Smad3 signalling was markedly activated in synovial tissues, which was associated with the loss of Smad7, and enhanced Th17 and Th1 immune response.12 TGF-β signalling also participates in the progression of fibrosis in SS.