Bcr/Abl mRNA and protein expression is readily detected in hematopoietic tissues from mice treated with STI571 or placebo, and in recipients of secondary BM transplants from STI571-treated animals.

Total RNA was prepared from placebo-treated (P) or STI571-treated (S) animals and analyzed by Northern blot by means of a P210^BCR/ABL–specific probe. At right are total RNA samples of blood (B) or BM (M) from secondary BM transplant recipients (indicated by number) from the donor animals STI571 no. 4 (lanes 8,9) or STI571 no. 6 (lanes 10-12). As a control, total RNA from the myeloid cell line 32D transduced with either P210 (B/A) or retroviral vector alone (neo) is shown at far right (lanes 13,14). Ethidium bromide (EtBr)–stained total RNA samples from spleen and peripheral blood of the secondary BM transplant recipients are shown (lower panel) to demonstrate equal RNA loading among the groups of samples. The position of P210^BCR/ABL mRNA is shown at the arrow.