Telomerase activity of iTR cells is shown. A) Telomerase activity was measured enzymatically in two iTR lines (iTR1 passage [p] 6, iTR2 p3), three iPS cells (IC1, ID4, and ID6, p10); parental PFF, p10; MEF, p4; and H9 hES cells, p41. The assay was performed in triplicate samples with 0.2 μg of total cell protein by using Trapeze-RT telomerase detection kit (Chemicon). Activities represent relative units of telomerase assessed by the quantity of primers (amole/sample) extended with telomeric repeats. Data are presented as means ± SEM. B) Relative production of estradiol by iPS cells and iTR cells. Values show the relative amounts of estradiol released into the medium after culturing two iPS cell lines (ID6 and IB3) and two iTR lines (iTR1 and iTR2) in F2 medium for 48 h (from Day 4 until Day 6 after passage when the cells were harvested). Bars (±SEM) represent estradiol concentrations (pg/ml) normalized to the total RNA amount (μg). ID6 and IB3 cells were at passage 38 and 35, respectively; iTR1 and iTR2 were at passage 35 and 19, respectively.