FIG. 5.

Induction of PTEN expression in U87 cells represses RNA Pol I transcription and concomitantly decreases the activation of Akt. (A) Induction of wild-type (wt) PTEN expression, but not PTEN-C124S, decreases the activation state of Akt. PTEN-inducible U87 cells (left panel) or PTEN-C124S-inducible U87 cells (right panel) were transfected with PrHuCAT. Cells were treated with vehicle or 1 μg/ml DOX for 6 or 24 h prior to harvesting the cells, as designated. Protein lysates were prepared, and 80 μg of protein was subjected to immunoblot analysis. Membranes were probed with antibodies as designated. (B) Wild-type PTEN, but not PTEN-C124S, decreases RNA Pol I-dependent transcription. Cells were transfected as described for panel A, total RNA was isolated, and RNA Pol I promoter activity was measured. An example of an autoradiograph is shown above the graphs. The values shown are means ± SEM from four independent determinations.