Both endogenous and exogenous Osx are increased by proteasome inhibitor treatment.

<p>A. Saos-2 cells were treated with MG-132 (20 µM) for various periods of time. Endogenous Osx protein was detected by Western blot analysis with an anti-Osx antibody. B. HEK 293T cells were transfected with Flag-hOsx plasmids and then treated with MG-132 (20 µM) for various periods of time. Exogenous Osx protein was detected by Western blot analysis with an anti-Flag antibody. C. Saos-2 cells were treated with lactacystin (10 µM) for various periods of time. Endogenous Osx protein was detected by Western blot analysis with an anti-Osx antibody. D. HEK 293T cells were transfected with Flag-hOsx plasmids and then treated with lactacystin (10 µM) for various periods of time. Exogenous Osx protein was detected by Western blot analysis with an anti-Flag antibody. β-actin served as a loading control. Results are shown for one of three independent experiments.</p>