Figure 4

TGF-β isoforms-induced decrease of PTEN protein content is XIAP-dependent. A) KLE and HeLa cells were treated with the indicated recombinant TGF-β isoforms (10 ng/mL) or with vehicle for 24 h. Levels of phosphorylated Smad2 (P-Smad2) were determined to monitor the activation of Smad pathway by TGF-β isoforms. Levels of PTEN protein and its ubiquitination were determined using western blot. Graphs represent densitometrical analysis of PTEN in Hela Cells. B) HeLa cells were pre-treated with 10 μM proteasome inhibitor MG-132 for 1 h before they were treated with the indicated recombinant TGF-β isoforms (10 ng/mL) or with vehicle, for 24 h. Levels of PTEN protein were determined using western blot. C) Before treatment with the indicated recombinant TGF-β isoforms (10 ng/mL) or with vehicle for 24 h, HeLa cells were transfected with XIAP shRNA or control (scrambled) shRNA for 24 h. PTEN and XIAP protein levels were determined using western blot. In all experiments, levels of phosphorylated Smad2 (P-Smad2) were determined to monitor the activation of Smad pathway by TGF-β isoforms and β-actin was used as a loading control. Graphs represent mean ± SE of three independent experiments. * p < 0.05.