Cell death in hTERT-transduced T-cell cultures in the absence of stimulation. CD4⁺ T-cell clone MoT-72 cells (top panel) and CD8⁺ T-cell clone AKR103 (bottom panel) transduced with hTERT–puro-transduced (•) or untransduced (○), respectively, were seeded at 1 × 10⁵ per mL 12 days after the last stimulation and cultured in medium containing IL-2 without stimulation for 100 days. Viable cells were counted weekly by trypan blue exclusion. † indicates death of the culture.