Tax neither impairs TGF-β1–induced Smad3 nuclear accumulation nor modifies Smad3 expression.

(A) HeLa cells were transfected with Flag-Smad3 and Tax expression vectors and were incubated either in the absence or in the presence of TGF-β1 for 30 minutes. Flag-Smad3 was visualized with an anti-Flag antibody, and Tax was detected with a rabbit anti-Tax antibody. Localization of the indicated proteins was analyzed by confocal immunofluorescence microscopy. Original magnification × 100. (B) HepG2 cells were transfected with Tax expression vector (Tax) or an empty expression vector (control) and treated with TGF-β1 for 1 hour. HepG2, MT2, and HUT nuclear (N) and cytoplasmic (C) lysates were subjected to immunoblot analysis with a polyclonal rabbit anti-Smad3 antibody and a mouse anti-Tax monoclonal antibody.