Figure 1.

Eµ-v-abl transgene expression is mosaic. (A) Expression of v-abl mRNA in sorted lymphoid cell populations determined by quantitative reverse transcriptase-PCR and shown relative to the expression of the housekeeping gene hydroxymethylbilane synthase (HMBS). Mean ± standard error of the mean (SEM), n = 3. Statistical comparisons with DP thymocytes are shown, *P < .05, **P < .01, Student t test. DP T, CD4⁺CD8⁺ thymocytes; T, Thy1⁺ lymph node cells; pre-B, B220⁺ sIgD/IgM⁻ bone marrow cells; B, B220⁺ lymph node cells; PB, plasmablasts (CD138⁺) produced by LPS stimulation of B cells in vitro; granulocytes, Mac1⁺Gr1⁺ bone marrow cells. (B) Western blot analysis of c-Abl and v-Abl protein expression in sorted lymphoid cell populations from WT and v-abl mice. Representative of 2 independent blots. Molecular weight (MW) markers are indicated (kDa). (C) Intracellular staining of DP thymocytes from WT (black curves) and v-abl (gray curves) mice using biotinylated anti-Abl antibody. As the antibody detects both c-Abl and v-Abl, cells expressing the transgene (right peak) have a higher level of total Abl protein. For the 3 v-abl mice shown here, 23%, 69%, and 82%, respectively, of the thymocytes express v-Abl protein, as indicated. (D) v-Abl expression level varies in different cell types. The relative mean fluorescent intensity (MFI) was determined by comparing the difference in MFI of WT and v-Abl expressing (right peak) cells in different lineages (relative MFI = MFI v-Abl-expressing cells/MFI WT cells). n = 12 mice from 3 independent experiments; mean ± SEM. Statistical comparisons with DP thymocytes are shown, ***P < .001, Student t test.