Fig. 6. Mutational disruption of TERT nucleolar localization does not affect its biological effects on maintaining telomere-length and extending replicative life-span in BJ fibroblasts. (A) Telomere lengths of corresponding stable BJ cells were analyzed at the indicated time points and showed that the telomere length of vector-infected BJ cells underwent a progressive shortening with the process of cultural propagation, whereas the telomere lengths both of GFP-TERT- and GFP–TERT-3A-expressing BJ cells were stably maintained during their successive propagation in culture. (B) Growth-curve analysis showed that vector-infected BJ cells ceased proliferation at around 65 PDs, whereas both GFP-TERT- and GFP–TERT-3A-expressing BJ cells still retained a robust proliferation rate at 92 and 86 PDs, respectively. (C) SA-β-gal assay showed that vector-infected BJ cells at 65 PDs became morphologically enlarged and displayed strong positive results of SA-β-gal staining, whereas both GFP-TERT- and GFP–TERT-3A-expressing BJ cells at the indicated time points were only faintly stained by the SA-β-gal assay and were without morphological changes. 100x magnification.