Phosphatidylinositol 3'-kinase, mTOR, and glycogen synthase kinase-3β mediated regulation of p21 in human urothelial carcinoma cells.

Background: The PTEN/Phosphatidylinositol 3'-kinase (PI3-kinase) growth factor signaling pathway plays a critical role in epithelial tumor development in a multitude of tissue types. Deletion of the Pten tumor suppressor gene in murine urothelial cells in vivo results in upregulation of cyclin-dependent kinase inhibitor p21. We have previously shown in mice that p21 expression blocks an increase in urothelial cell proliferation due to Pten deletion.