TGF-β stimulates MCP-1 promoter activity. (A) TGF-β and Smad3/Smad4 enhanced the activity of the MCP1 promoter in HMVECs. HMVECs were transfected with MCP-1 1040-luciferase or cotransfected with Smad3 and Smad4. After being serum-starved for 24 hours, the cells were treated with or without TGF-β1 for another 20 hours prior to being harvested for luciferase activity measurement. (B) The −1040-bp to −540-bp region of the MCP-1 promoter was important to respond to TGF-β stimulation. HepG2 cells were transfected with various constructs as indicated. The cells were then harvested for luciferase measurement 40 hours later. (C) Smad7 inhibited the TGF-β–induced expression of the 1040-luciferase reporter. HepG2 cells were transfected with reporters together with or without Smad7. Luciferase assay was performed similarly as in panel A. The asterisk indicates a significant difference compared with the control (*P < .05; n = 3). Error bars indicate SD.