Expression of collagen type I, α-smooth muscle actin (α-sma) and telopeptide lysylhydroxylase (TLH) in healthy fibroblast like synoviocytes (FLSs) upon stimulation with transforming growth factor (TGF)-β and synovial fluid (SF). (a) Expression of collagen type I alpha 2 chain (COLIA2)/β2-microglobulin (β2M) mRNA, (b) α-sma/β2M mRNA and (c) TLH/β2M mRNA were measured after stimulation of healthy FLSs with 1 ng/ml TGF-β or 1/10 diluted SF from rheumatoid arthritis patients. TGF-β increased COLIA2 expression, but had no effect on α-sma expression. Stimulation of healthy FLSs with synovial fluid from RA patients (RASF) did not lead to an increase in COLIA2/β2M but did induce α-sma/β2M mRNA expression. TLH expression was induced by both TGF-β and SF. Horizontal lines indicate the median; diamonds indicate FLSs from individual subjects. * indicates P < 0.05.