F317V causes resistance to PD166326 while preserving sensitivity to imatinib. Ba/F3 cells transfected with Bcr-Abl wild-type (wt) or Bcr-Abl F317V were incubated for 24 and 48 hours without and in the presence of imatinib (wt, ×; F317V, □) or PD166326 (wt, +; F317V, □) at the indicated concentrations. Proliferation was measured in an MTS-based assay. There were 2 independent experiments performed. Values are expressed as mean of triplicates. Bars: ± SE. Representative results of one experiment after 48 hours of incubation are shown. OD indicates optical density.