Similarly, we also observed a significant up-regulation in the mRNA expression of TSP-1, TGF-β1, CTGF and VEGF in RA-FLS from the lower chamber of the co-culture compared with NH-FLS, as quantified by real-time PCR analysis (p < 0.05, Figure 1B). Here, TGFB1 is linked to rheumatoid arthritis.