Induction of telomerase activity by E₂ in normal and transformed human prostate epithelial cells. Cell extracts from (a) normal PrECs (1 μg) and fresh explants from two BPH lesions (1 μg), (b) three PCa specimens (0.2 μg), and (c) PCa cell lines LNCaP, DU145, and PC-3 (0.1 μg), cultured in the absence or in the presence of E₂ (10^–7 M) for the indicated times, were assayed for telomerase activity by TRAP assay in the presence of an internal control (IC; 36 bp). As positive and negative controls, cell extracts (0.1 μg) from telomerase-positive HeLa cells were assayed before and after heat inactivation (HeLa and HeLa H.I.), respectively. Panels relative to the internal control are shown at a lower detection exposure.