Pim1 expression is insufficient to convert benign human prostate cells (RWPE1) to malignancy. (A) 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed there was no difference in in vitro cell proliferation between control and Pim1-expressing RWPE1 cells. (B) Representative H&E images of grafts. RWPE1-Neo (N = 5); RWPE1-Pim1 (N = 7). Scale bars: 100 μm. (C) Quantitation of proliferation and apoptosis in xenografts after immunostaining for Ki67 and activated Caspase 3, respectively. *P < 0.05.