Differentiation potential of BM cells transduced with D816Y/V KIT and control vectors. (A) Total numbers of colonies from 10⁵ cultured WT (wt) or Cbfb^+/56m; Tg(Mx1-Cre) BM cells transduced with retroviral vectors containing WT KIT, KIT^D816V or GFP and sorted for GFP expression. Wt + GFP indicates WT BM cells transduced with GFP vector alone; Wt + KIT wt, WT BM cells transduced with WT KIT vector; and MxCre-CM + GFP, KIT wt, or D816Y, Cbfb^+/56m; Tg(Mx1-Cre) BM cells transduced with GFP, Wt KIT, or KIT^D816V vector, respectively. The numbers above the bars are average colony numbers for the group. (B) Ratio of total colony numbers from 10⁵ cultured WT or Cbfb^+/56m; Tg(Mx1-Cre) (MxCre-CM) BM cells transduced with GFP versus those transduced with WT KIT. (C) Types of colonies formed from transduced Cbfb^+/56m; Tg(Mx1-Cre) BM cells. CFU indicates colony-forming unit; G, granulocyte; E, erythrocyte; MM, monocyte and megakaryocyte; and GM, granulocyte and monocyte. All BM cells were sorted for GFP⁺ cells before plating. (D) Comparison of annexin V⁺ cell numbers (percentage) between the KIT (both WT and 816 mutants)–transduced (GFP⁺) and untransduced (GFP⁻) BM lin⁻ cell populations, for both WT and Cbfb^+/56m; Tg(Mx1-Cre). (E) Comparison of annexin V⁺ cell numbers (percentage) between the WT and Cbfb^+/56m; Tg(Mx1-Cre) BM lin⁻ cell populations that were transduced with WT KIT or KIT^816Y/V. (F) BrdU⁺ cells in KIT (WT and 816 mutants)–transduced BM cells.