TWEAK actions on renal cellsin vitro. (A) TWEAK modulates mesangial cells proliferation. The proliferation of MMC is significantly increased following stimulation with TWEAK (10–1000 ng/ml) for a 24-hour incubation. Data are expressed as mean ± SD of five independent experiments. **P < 0.001 vs. control; *P < 0.05 vs. control. (B) MCP-1 secretion in response to TWEAK stimulation is dose and time dependent. MCP-1 protein levels in TWEAK stimulated MMC supernatants are shown. Data are expressed as mean ± SD of three independent experiments. *P < 0.05, TWEAK at 10, 100 ng/ml vs. control. (C) TWEAK stimulates podocyte motility as evaluated by wound healing assay. After the scraping of the podocyte cell layer, cells have started to migrate into the wound track. The wound closures were significantly enhanced in the presence of TWEAK (100, 1000 ng/ml) at 24 hours. Compared with the control, TWEAK enhanced directed cell migration in differentiated podocytes. Data are expressed as mean ± SD of five independent experiments. *P < 0.05, TWEAK at 100, 1000 ng/ml vs. control 24 hours. Scale bar = 200 μm.