Fig. 1. hTERT does not reverse the senescent phenotype. (A) Lenti-hTERT confers telomerase activity. Senescent (S) or pre-senescent (P) WI-38 (WI) cells were infected with lenti-hTERT, lenti–GFP or pBABE-hTERT, and telomerase activity was measured using the TRAP assay, as described in Materials and methods. ‘+’ is a positive TRAP control, and ‘–’ and ‘Heat inactivated’ are negative controls. (B) Lenti-hTERT alters telomere length in pre-senescent, but not senescent cells. Terminal restriction fragment (TRF) lengths in P- or S-WI cells infected with lenti–GFP (GFP) or lenti-hTERT (hTERT) were determined as described in Materials and methods. (C) Lenti-hTERT does not alter senescent morphology. S-WI cells were infected with lenti–GFP (+GFP) or lenti-hTERT (+hTERT), and viewed and photographed 7 days later.