Telomerase activity in candidate HSC after 5 days of culture. TRAP products using CHAPS extracts of total viable cells derived by culturing purified candidate HSC from BM4 for 5 days in SCF (lanes 1 and 2), FL (lanes 3 and 4), IL-3 (lanes 5 and 6), SCF + FL (lanes 7 and 8), SCF + IL-3 (lanes 9 and 10), FL + IL-3 (lanes 11 and 12), and SCF + FL +

IL-3 (lanes 13 and 14). TRAP products were resolved on a 15% polyacrylamide gel, dried, and exposed to film for 48 hours. The intensity of the signals was analyzed by a densitometer using ImageQuant program and normalized to that of the internal control. Cellular extracts from BM1 and BM3 yielded similar results.