Telomerase activity in candidate HSC before culture. TRAP products were generated from 2 μL of CHAPS extract (1,000 cell equivalents) in the presence (+) or absence (−) of RNase A. TRAP products generated from sorted cells on day 0 from 4 different cadaveric marrow (lanes 1 to 8); lane 9, no extract; lane 10, 1 amol M2R8 standard. Arrow indicates the position of the 35-bp amplified internal control.