Figure 4. TGF-β levels measured by enzyme-linked immunosorbent assay (ELISA). CYS decreased TGF-β levels in a dose-dependent manner (p=0.011; Kruskal–Wallis test). PHA-stimulated PBMCs served as the positive control and unstimulated PBMCs served as the negative control. *: statistically significant by the Mann–Whitney U test.