Exogenous Runx1 restores granulopoiesis and diminishes monopoiesis in Runx1-deleted marrow cells. (A) Marrow mononuclear cells isolated from Runx1(f/f);Mx1-Cre mice exposed to pIpC and subsequently to 5-FU were transduced with RUNX1-ER or with the pBabePuro vector, selected with puromycin, and then plated in methylcellulose with IL-3, IL-6, and SCF with or without 4HT. The absolute number of CFU-Gs or CFU-Ms per 1E4 cells plated in 3 independent transduction experiments is shown. (B) The proportion of CFU-Gs or CFU-Ms among these myeloid CFUs is shown (mean and SE from 3 determinations). (C) Marrow isolated from Runx1(f/f) mice exposed to 5-FU was transduced with pBabePuro or pBabePuro-Cre for 3 days, followed by puromcyin selection for 2 days. Cells were then plated in methylcellulose with IL-3, IL-6, and SCF, and CFUs were enumerated 8 days later. Shown is the percentage of CFU-Gs and the percentage of CFU-Ms among CFU-Gs plus CFU-Ms (mean and SE from 3 determinations).