AML1-ETO enhances expansion of primitive HPCs.

HPCs were transduced with the indicated virus, expanded for 6 days in cytokine-driven culture, and plated onto the MS-5 stromal cell line in triplicate flasks. Nonadherent cells were counted by trypan blue and analyzed weekly for GFP expression by flow cytometry. (A) Percentage of GFP-expressing cells over time. (B) Total number of nonadherent cells over time. (C) Total number of GFP⁺ cells during the 5-week stromal cell culture period. Three independent experiments yielded essentially the same results; a representative experiment is shown.