Similar tyrosine phosphorylation of BCR-ABL in BCR-ABL– transduced +/+ and SHIP^–/– leukemic murine cells. Shown are Western blot analyses of cell lysates from the spleen and liver of a control (MIG-transduced) mouse (lanes 1-2), the spleen and liver of sick mice initially receiving transplants with 10³ and 5 × 10³ BCR-ABL–transduced Sca-1⁺lin^– GFP⁺ cells (lanes 3-6), and cell lysates from the spleen and liver of sick mice injected with similar numbers of Sca-1⁺lin^–GFP⁺ cells from BCR-ABL–transduced SHIP^–/– cells (lanes 7-9). Lysates from equal numbers of cells were separated on 8% polyacrylamide gradient gels. The filter was first probed with an antiphosphotyrosine (4G10) antibody, then stripped and reprobed with an anti-ABL antibody (8E9). The positions of prestained molecular weight markers are indicated on the left side of the blot.