PTEN and prostate intraepithelial neoplasia: To identify the potential cell type of the Pten-deficient prostate cancer, we performed double immunofluorescent staining to verify the presence of cytokeratin 5 (CK5+)-expressing basal cells and cytokeratin 8 (CK8+)-expressing lumen epithelial cells from the normal, BPH, PIN and prostate cancer samples in the R26-Ptenfx/fx mice compared with the controls.