Growth characteristics of BCR-ABL–transformed Baf/3 cells resistant to STI571.

(A) Cell viability assessed by trypan blue exclusion of Baf/BCR-ABL cells (⧫) and Baf/BCR-ABL cloned in 1 μmol/L STI571 (Baf/BCR-ABL-r1) (▪), treated (▵) or not treated (X) with 1 μmol/L STI571. (B) Cell proliferation of Baf/3 cells, Baf/BCR-ABL-s, and Baf/BCR-ABL-r1 under the effect of various concentrations of STI571, as assessed by MTS uptake. Results are expressed as the mean OD₄₉₀ of quadruplicate cultures, which is directly proportional to the number of viable cells.