Jiang, Strand, Fernandez et al. 349 Figure 2. Generation and characterization of human prostate-speciﬁc epithelial NHPrE1 and BHPrE1 cells. A: Morphology of NHPrE1 and BHPrE1 cells at passages 32 and 27, respectively. Scale bar ¼ 50 lm. B: NHPrE1 cells grow more slowly than BHPrE1 cells in a cell prolifera- tion assay. C: Polymerase chain reaction detection of hPSA, rPb, and mPb in the genomic DNA conﬁrms the human origin of NHPrE1 and BHPrE1 cells. D: Ku70 staining is 100% positive by immunoﬂuorescence in both NHPrE1 and BHPrE1 cells, suggestive of human origin. Scale bar ¼ 50 lm. E: Active export of bis-benzimide (Hoechst 33342) identiﬁes a side population of prostate epithelial cells in NHPrE1 and BHPrE1 cells by ﬂow cytometry analysis (outlined), which is reduced upon the addition of verapamil treatment (right), suggestive of a stem cell popula- tion. Abbreviations: BHPrE0, primary cultured benign human prostate epithelial cells isolated from a prostate surgical sample; hPSA, human prostate-speciﬁc antigen; mPb, mouse Probasin; NHPrE0 (NHP8), primary cultured ‘‘normal’’ human prostate epithelial cells isolated from a donated, 41-year-old, healthy, male prostate; rPb, rat Probasin. results for the parental NHPrE0 and BHPrE0 cells (which were apparently genetically intact with minimal chromosomal changes). The copy number changes for chromosome regions were examined using DIGMAP analysis to compare the four cell types (NHPrE0, NHPrE1, BPHPrE0, and BHPrE1) as shown in Figure 4B. The main differential regions between NHPrE1 and BHPrE1 are 17p13.1, 10q23.3, 3p21, 5p15.33, and 9p21. Interestingly, PTEN was ampliﬁed in NHPrE1 cells www.StemCells.com