Retention of CD34 expression during proliferation in the absence of added growth factors.

The percentage of cells that remained CD34⁺ is shown on a peak-by-peak basis for divisions 0 to 4 for CML progenitor cells cultured in SFM in the presence (+GF) or absence (−GF) of GFs. As shown, the proportion of cells that retained CD34 expression was greater in the absence than in the presence of added growth factors after the second division.