Telomerase activity in hTERT-transduced T lymphocytes during long-term culture. Telomerase activity in cultures of CD4⁺ naive T-cell clones as well as polyclonal populations transduced with hTERT was analyzed using the TRAP assay. After transduction cells were sorted for GFP expression and further expanded. Two thousand cells of each population were analyzed at different time points during long-term expansion. High stable telomerase activity was detected for all the analyzed samples 10 days after stimulation as indicated throughout the whole culture period (day 64, 119, and 212 after transduction). Negative control (n.c.) indicates no cell extract; positive control, extracts obtained from K562 cell line.