Induction of factor-independent growth in Ba/F3 cells by the expression of #ABL chimeras. (A) Expression levels and tyrosine phosphorylation of the transgenes expressed in Ba/F3 cells. (B) Factor-independent growth of Ba/F3 cells expressing the indicated transgenes. (C) Effect of 1 μM STI571 on IL-3–independent growth of Ba/F3 cells expressing p185^(BCR-ABL) or the indicated #ABL chimeras (mean of 3 independent experiments ± SD). (Left) Without STI571. (Right) With STI571.