Figure 3.
Activation of PI 3-kinase or down-regulation of PTEN in human tumors. A: In vitro PI 3-kinase assay of the anti-p85 immunoprecipitates from nine tumor specimens that exhibit elevated AKT1 kinase activity. Elevated levels of PI 3-kinase activity were detected in cases 4, 6, and 7. B: Immunostaining of paraffin sections of prostate adenocarcinomas with anti-PTEN (left) and anti-phospho-Ser473 Akt (right) antibodies. PTEN is negative in tumor cells (black arrows), but positive in hyperplastic glands (arrowhead). However, phosphorylation of Akt was only detected in tumor cells (black arrow).