Plag1 and PLAGL2 increase proliferation of hematopoietic progenitor in vitro by inducing entry into S phase. (A) Serial replating (P1 to P3) of 10⁴Cbfb-MYH11-expressing bone marrow cells infected with MIG (□), MIG-Plag1 (▪), or MIG-PLAGL2 (▦) and cultured in methylcellulose culture for 7 days. (B) Representative images of colony morphology at day 7. (C) Lineage distribution colony-forming units (CFUs) from P1 analyzed by cytospin of individual colonies. Colony types are indicated as granulocytic (G; ▧), monocytic (M; ▥), granulocytic and monocytic (GM; ▪), mix (▦), and blast (▤). (D) Cell-cycle analysis of sorted bone marrow cells expressing Cbfb-MYH11 and MIG-Plag1 (gray line), MIG-PLAGL2 (dotted black line), or MIG (solid black line) and stained with propidium iodine. (E) The Igf2 RELs determined by quantitative PCR in E14.5 total embryo (lane 1), MIG wild-type bone marrow (lane 2), MIG-PLAGL2 wild-type bone marrow (lane 3), MIG Cbfb-MYH11 bone marrow cells (lane 4), MIG-PLAGL2 Cbfb-MYH11 bone marrow (lane 5), Plag1/Cbfb-MYH11 leukemias (lanes 6-8), PLAGL2/Cbfb-MYH11 leukemias (lanes 9-11), and leukemias not overexpressing Plag1 or PLAGL2.^12-15  Values were normalized to Actb expression levels. Error bars indicate standard error from triplicate experiments.