Mature and progenitor myeloid cell populations are expanded in pIpC-treated Runx1-excised mice. (A) Plotted are the mean ± SD of total (P < .05), myeloid (P < .05), BFU-E (P = .5), and mixed-lineage colonies (P = <.05) per 2 × 104 BM cells plated in vitro from pIpC-treated Runx1F/F (□) and Runx1F/F—Tg(Mx1-Cre) (▪) mice. Results are the average of 3 experiments performed in duplicate. (B) Representative cytospin from mixed-lineage colony derived from Runx1F/F—Tg(Mx1-Cre) BM (Wright-Giemsa staining; original magnification, × 600). Red arrowheads indicate representative erythroid elements. Green arrowheads denote myeloid and monocytic forms. (C) Representative EtBr-stained 3% agarose gel of Runx1 PCR products from single GM or mixed-lineage colonies derived from Runx1F/F—Tg(Mx1-Cre) (lanes 1-20) and Runx1F/F (lanes 21-25) mice. Of 70 Runx1F/F—Tg(Mx1-Cre) colonies evaluated, 9 (12.8%) failed to show any amplification, 5 of 61 (8.2%) indicated partial excision, and 56 of 61 (91.8%) were completely excised. Tail and embryo genomic DNA controls are as indicated. (D) Gr1 and Mac1 staining of BM from representative CXB6F1 mice 154 days after pIpC induction. Numbers indicate percentages of cells gated in each respective quadrant.
