AP23464 inhibits proliferation of Ba/F3 cells expressing WT Bcr-Abl or Bcr-Abl mutants Q252H, Y253F, E255K, M351T, and H396P, but not mutant T315I or parental Ba/F3 cells. Parental Ba/F3 cells supplemented with IL-3 or Ba/F3 cells expressing WT or mutant Bcr-Abl protein were plated in quadruplicate at 5 × 10³ cells/well in 96-well plates with AP23464 included in the media (0, 5, 10, 20, 40, 80, 160, or 320 nM). Results from day 2 MTS assays were used to construct best-fit curves and calculate the cellular IC₅₀. The mean based on 4 replicates was calculated in the absence of inhibitor and for each concentration of AP23464. Means ± SE were generated from 3 independent experiments and reported as the percentage absorbance of control. Error bars are omitted for clarity.