Transwell co-culture system Cytoselect 24-well cell migration assay kit (Cell Biolabs, Inc.) was used. HK cells without TGF-b 1 treatment with/without PBMCs were co-cultured in the lower well with complete media and HK-2 cells pre-stimulated with TGF-b 1 (10.0, 1.0 and 0.1 ng/ ml) for 24 hrs followed by three careful washes by PBS or HK-2 cells without TGF-b 1 stimulation were added to 2 mm pore size polycarbonate membrane cell culture inserts. Then, after 24 hrs of incubation, TGF-b 1 concentration in the lower well media was measured by TGF-b 1 ELISA.