Expression analysis of retroviral FLT3 constructs. (A) Flow cytometric analysis of murine bone marrow retrovirally transduced with FLT3 high-expressing constructs. A fluorescein isothiocyanate (FITC)-versus-PE channel dot plot is shown without compensation to exclude autofluorescent cells. The EGFP-positive population shifts on a diagonal to the right. The circle indicates the EGFP-positive (FLT3) cells. Numbers in top left corners indicate the percentage of EGFP⁺ cells. (B) Western blot analysis of bone marrow shown in panel A. Bone marrow cells were not starved from the cytokines of the infection procedure before preparation of total cell lysates. Similar transduction efficacy for different FLT3 mutants results in equal FLT3 protein expression and activation of downstream targets in murine bone marrow. The cells loaded in the first lane (“untransduced”) were treated like the FLT3-transduced cells but without retrovirus during the infection procedure. (C) Comparison of FLT3 protein expression of the high- and low-expressing FLT3-ITD constructs in Phoenix E cells.