Runx2/AML3 and Runx3/AML2 have the capacity to rescue the hematopoietic defect of AML1-deficient P-Sp regions. (A) The efficiency of retrovirus-mediated gene transfer of Runx2/AML3 or Runx3/AML2 was estimated by infecting NIH3T3 cells. Retrovirus-infected cells were evaluated by the expression of GFP (shaded histograms). Also shown are the noninfected NIH3T3 cells (open histograms). (B) Expression of 3 Runx proteins (AML1, Runx2/AML3, and Runx3/AML2) in infected NIH3T3 cells. The expression is monitored by immunoblotting of whole-cell lysates with anti-Flag. (C) Both Runx2/AML3 and Runx3/AML2 have the capacity to rescue the hematopoietic defect of AML1-deficient P-Sp regions. Shown are phase-contrast microscopic views of these cultures at 14 days visualized using a Nikon Eclipse TE2000-U (Nikon Sankei) at a magnification of × 100.