TGF-β1 acts through TβRII and ALK5 to inhibit aromatase transcription. A) Cells were transfected with Arom -714 construct, the control vector pCMV5 or dominant negative TβRII. At 24 h after transfection, they were treated with the control medium or TGF-β1 (1 ng/ml). B) Cells were transfected with Arom -714 construct, control vector pCMV5, the dominant negative ALK5 (ALK5-kd) and the constitutively active ALK5 (ALK5-ca). A β-galactosidase expression vector (0.5 μg) was simultaneously co-transfected into cells for normalizing transfection efficiency.