STI-571 does not inhibit other Jak/Stat signaling cascades.

(A) Mo7e or MBA cells were pretreated with nothing or STI-571 (5 μM) for 30 minutes and subsequently treated with IFN-α (500 U/mL; 30 minutes) before cell lysates were collected and analyzed for Stat-1 activation by immunoblotting with phospho–Stat-1–specific antibody. The blot was stripped and reprobed with anti–Stat-1 as a control. (B) Daudi (left) or BV-173 (right) cells were treated with 5 μM STI-571 alone or subsequently treated with IFN-α, as described above, before cell lysates were analyzed for Stat-1 activation with anti–p-Stat-1. Anti–p-Stat-1 also recognizes activated bcr-abl (as described in Figure 2) and can be used as a control to demonstrate that STI-571 reduces bcr-abl activation without affecting IFN-α–mediated Stat-1 phosphorylation in BV-173 cells.