Fig. 5. mTERT overexpression protects ES cells from stress-induced apoptosis. Vector-transfected (left) and mTERT-overexpressing (right) ES cells were treated with 0.6 µg ml^–1 doxorubicin (top) or 1 mM H₂O₂ (middle) for 12 hours. Untreated controls are shown at the bottom. Apoptosis was determined by staining cells with FITC-conjugated annexin-V and PI, and analysed by flow cytometry. Representative results are shown from one of the experiments in duplicate.