Comparison of CML and lymphoid blast crisis models. Lin⁻ cells from bone marrow of wild-type, p16^INK4A/p19^ARF-null, or p19^ARF-null donors were isolated as described in “Generation of murine models.” The cells were transduced with vectors coexpressing p210BCR/ABL and EGFP, followed by injection into sublethally irradiated wild-type recipient mice. Leukocytes from peripheral blood of the recipients were collected for lineage and morphological analysis approximately 2 to 3 weeks after transplantation. (A) Expression of p210BCR/ABL in wild-type donors resulted in the development of CML-like disease in recipients. Histological staining of peripheral blood shows mature granulocytes (G), FACS analysis indicates that almost all EGFP⁺ cells are Mac1⁺/Gr1⁺. (B) Injection of p210BCR/ABL-expressing cells from p16^INK4A/p19^ARF or p19^ARF-null donors showed high levels of immature lymphoblasts (LBs) in recipient mice. The immunophenotype of EGFP⁺ cells is almost entirely B220⁺/CD19⁺, indicating the disease type is B-lineage acute lymphoblastic leukemia (B-ALL).