Knockdown of Smad3 inhibits ALK4(TD) and ALK7(TD) stimulated transcription. LβT2 cells were transfected as described with ALK4(TD) or ALK7(TD) in the presence of a Smad3 shRNA expression vector or empty vector (pBS/U6). Luciferase activity from the Fshb reporter was measured 24 hr post transfection. Data are from three independent experiments with treatments performed in triplicate. Bars with different letters differed significantly from one another.