Developmental defects of thymocytes in Cbfb-MYH11 chimeras. (A) Identification of Ly9.1+ and Ly9.1− thymocytes from a Cbfb-MYH11 chimera. (B) Analysis of thymocyte development in the Cbfb-MYH11 chimeras by FACS. Top panels show CD4 and CD8 distribution of Ly9.1+ and Ly9.1− cells. Bottom panels show CD44 and CD25 distribution of DN cells from Ly9.1+ and Ly9.1− cells. (C) The annexin V and 7AAD stainings of Ly9.1+ and Ly9.1− cells are displayed. (D) CD4 expression in immature thymocytes. The left panel shows a representative histogram overlay of CD4 expression in TCRβloFSChiCD8−/lo thymocytes from Ly9.1+ and Ly9.1− cells. The right panel shows the MFI of CD4 expression in TCRβloFSChiCD8−/lo cells.