PTEN expression in human coronary VSMC <i>in vitro</i>.

<p><b>A</b>, PTEN-expression is not upregulated by mechanical stress in VSMC. Lysates of cells exposed to mechanical forces using a stretching device were analyzed by western blotting using specific antibodies. <b>B</b>, Lysates of SMC exposed to growth medium (FCS). PTEN expression was not upregulated after 24 h. Protein expression was determined using specific antibodies. Detection of Cdk4 served as loading control. <b>C</b>, Lysates of SMC exposed to oxidative stress using 500 µM H₂O₂. PTEN upregulation was triggered by oxidative stress within 24 h. Detection of p53 and Cdk4 served as apoptotic marker and loading control, respectively. <b>D</b>, The upregulation of PTEN protein levels was quantified by densitometric analysis of immunoblots (n = 3; *<i>P</i><0.05). <b>E</b>, The upregulation of PTEN activity is mediated by H₂O₂-induction. Shown is a phosphatase activity assay of immunoprecipitated protein from lysates of HcASMC with and without 24 h H₂O₂–treatment. Immunoprecipitations from lysates employing an IgG iso-antibody without H₂O₂-treatment with and without bpV supplementation, an anti-PTEN-antibody without H₂O₂ and bpV treatment and an anti-PTEN-antibody with H₂O₂– and bpV-treatment served as controls. Results are expressed as mean OD650 ± SD using an ELISA plate reader (^#<i>P</i><0.001, *<i>P</i><0.001; n = 4).