Effects of podocalyxin (PODX)/β-catenin (β-cat) signaling on p38 mitogen-activated protein kinase (MAPK) activities in glioblastoma multiforme (GBM) cells.

<p>In (<i>A</i>) LN-229 and (<i>B</i>) U-118 MG GBM cells, the p38 MAPK activity was determined with a p38 MAPK Assay kit (Cell Signaling Technology) by measuring phosphorylation of ATF2, a substrate of activated p38 MAPK. The levels of phosphorylated ATF2 (p-ATF2) were determined with western blot in normal control cells (NC, lane 1), cells stably transfected with the empty pcDNA3.1 vector (VC, lane 2), cells stably transfected with PODX (lane 3), cells stably transfected with PODX and treated with selective p38 mitogen-activated protein kinase (MAPK) inhibitor PD169316 (25 µM) for 30 hours (PODX+PD, lane 4), cells stably transfected with PODX and treated with selective β-cat signaling inhibitor CCT031374 (50 µM) for 30 hours (PODX+CCT, lane 5), cells stably transduced with scramble control shRNA (SC, lane 6), cells stably transduced with PODX-shRNA (lane 7), and cells stably transduced with PODX-shRNA and stably transfected with constitutively active (ΔN151) β-cat (PODX-shRNA+active-cat, lane 8). The p-ATF2 content/p38 MAPK activity was shown as fold changes to that of NC (designated as 1). Each experiment was repeated for three times in duplicates. Data values were expressed as Mean+SD. ^a<i>p</i><0.05 vs. controls (NC, VC and SC); ^b<i>p</i><0.05 vs. PODX; ^c<i>p</i><0.05 vs. PODX+PD; ^d<i>p</i><0.05 vs. PODX+CCT.