Development of SCLL in ZNF198-FGFR1–transduced BM stem cells. (A) The ZNF198-FGFR1 fusion gene was cloned into the MIG vector containing the murine stem cell virus promoter and GFP cDNA linked by the internal ribosome entry site (IRES). (B) Schematic representation of the experimental approach of retrovirus transduction and transplantation of ZNF198-FGFR1. (C) May-Grünwald-Giemsa staining and (D) hematometric analysis of peripheral blood smears show a significant (P < .05) increase in WBC counts with a population of immature or blast cells in leukemia mice (C bottom right panel). (E) Flow cytometric analysis shows a right shift for both Gr-1–positive and Mac-1–positive myeloid cells in ZNF198-FGFR1 primary recipients expressing GFP. (F) The spleens and livers in leukemia mice are significantly (P < .05, P < .01, respectively) enlarged compared with normal mice. (G) ZNF198-FGFR1 induced distinct SCLL in mice, as evidenced by hepatosplenomegaly (i-ii), and enlarged LNs, Peyer patch (iii), mesenteric (iv), renal and lumbar (v), popliteal (vi), and superficial cervical and axillary (vii) LNs. (H) Molecular imaging shows all LNs displayed GFP fluorescence (see arrows). (I) Histologic analysis shows frequent hypercellularity in BM and infiltration of lymphocytes into various organs of ZNF198-FGFR1 recipients.