Effect of TGF-β treatment on the endoglin promoter activity. BAEC were transiently transfected with the indicated promoter constructs and TGF-β1 was added 24 hours posttransfection to half of the transfected cells. Luciferase activity was determined 48 hours after transfection. Correction for transfection efficiency was made by cotransfection with β-galactosidase expression vectors and parallel transfections with the pGL2-SV40 and pXP2 vectors, used as positive and negative controls, respectively. The promoter activity of the pGL2-SV40 vector was arbitrarily considered as 100. (A) Effect of increasing concentrations of TGF-β. BAEC were transiently transfected with the pCD105 (−400/+341) plasmid and stimulated with TGF-β1 at the concentrations indicated. This is a representative experiment of five separate experiments. (B) TGF-β inducibility in different endoglin promoter constructs. BAEC were transiently transfected with the indicated plasmids and incubated either in the absence (▪) or in the presence (▨) of 10 ng/mL of TGF-β1. The TGF-β–inducible reporter construct p3TP-lux was included as a positive control. The P-cadherin promoter construct pxp-200 failed to respond to TGF-β. A representative experiment of five different experiments is shown. (C) A representative scheme of the different constructs used with the relative location of TGF-β–responsive elements is shown. TCE, TGF-β control element; TIE, TGF-β inhibitory element; TAE, TGF-β activation element; Mad, Mothers against decapentaplegic complex.