Myeloid-lineage phenotype of leukemic cells in RE;c-Kit^D814V and RE;c-Kit^{T417IΔ418-419} mice. (A) Representative FACS analysis of AML cells harvested from BM and spleen of Bex;Vex control and moribund RE;c-Kit^D814V and RE;c-Kit^{T417IΔ418-419} mice. Cells were gated for Bex⁺Vex⁺ expression and then analyzed for Mac-1, Gr-1, and CD115 (M-CSFR) expression. (B) Wright-Giemsa–stained cytospins of FACS-purified Bex⁺Vex⁺ myeloid-gated BM cells from control or moribund animals demonstrating a high frequency of blast forms in leukemic RE;c-Kit^D814V and RE;c-Kit^{T417IΔ418-419} mice (original magnification ×630). (C) Myeloid CFU assays performed by plating 1 × 10⁴ FACS-purified Bex⁺Vex⁺ myeloid scatter-gated BM cells from Bex;Vex control, nonleukemic RE (39-45 weeks post-transplant), nonleukemic D814V (3-17 weeks post-transplant), moribund RE;c-Kit^D814V, and moribund RE;c-Kit^{T417IΔ418-419} mice in M3434 methylcellulose. Each data point represents the total number of myeloid CFU from an independent animal counted 7 to 12 days after plating.