Proliferation and differentiation potentials of AML1a-expressing hematopoietic cells ex vivo. (A) FACS profile of the lineage-negative fraction of bone marrow cells infected with the TetOFF-GFP-tetO-AML1a retrovirus and cultured ex vivo. (B-C) Colony formation abilities and cell proliferation in liquid culture of Sca-1⁺ and Sca-1⁻ cells in the Lin⁻ fraction. BM cells infected with TetOFF-GFP-tetO-AML1a retrovirus were sorted for GFP+. Lin⁻ cells were further fractionated into Sca-1⁺ and Sca-1⁻ and assayed for colony formation (B) and growth in liquid culture (C). (D) FACS profiles of the lineage-negative fraction at the indicated time after Dox treatment. (E) Lymphoid differentiation potential of Sca-1⁺ cells. B-cell (left) and T-cell (right) differentiation abilities of Sca-1⁺ cells in the presence of Dox and cultured with IL-7 + Flt-3 ligand on OP9 (left) and OP9-DLL1 (right) stroma cell layers. Erythroid (F) and (G) megakaryocytic differentiation of Sca-1⁺ cells in the presence of Dox and induced by erythropoietin and thrombopoietin, respectively. FACS analysis for erythroid-specific TER119 expression, hemoglobin staining of a colony, and morphology of erythroid cells (arrow heads) are presented in panel F. A photomicrograph showing a megakaryocyte (arrowhead) is presented in panel G. (F-G) May-Grunwald Giemsa staining. Original magnifications, ×1000 (SPlan100 100×/1.25 oil 160/0.17 objective). Typical results from at least 3 independent experiments are presented in panels A through G.