Day 3 CFSE profile for CD34⁺ cells derived from normal mobilized peripheral blood.

Upper histograms demonstrate that in the presence of added growth factors, normal CD34⁺ cells were stimulated to undergo 6 or fewer divisions by day 3 and that this pattern was not significantly altered by the addition of STI571. Lower histograms confirm that, in the absence of added growth factors, normal CD34⁺cells were unable to execute even a single division regardless of whether STI571 was present. PBSC indicates peripheral blood stem cells.