Specificity and activity of WP1130 in Bcr-Abl–expressing cells. (A) K562 cells were treated with 5μM WP1130 or DMSO (control) for 2 hours before equal amounts of detergent-soluble cell lysates were immunoblotted for the protein indicated. (B) eGFP-Bcr-Abl–transformed BaF3 cells were left untreated or treated with 5μM imatinib or WP1130 for 2 hours before analyzing equal protein cell lysates for Bcr-Abl and actin by immunoblotting. (C) BaF3 cells transformed by eGFP-Bcr-Abl without (W/T) or with the T315I Bcr-Abl mutation were treated with imatinib or WP1130 at the indicated concentration for 72 hours before assessing cell growth and survival by 3-(4,5-dimethylthiazol-2-yl)-2,5,-diphenyl tetrazolium bromide staining.^7,20  The results represent the average ± SD of 4 replicates. Similar results were obtained in 2 additional independent studies. (D) BaF3 cells transformed with eGFP-Bcr-Abl were treated with 5μM imatinib or WP1130 for 2 hours before cells were fixed with paraformaldehyde, cytospun onto slides, and stained with Hoechst. Digital images were captured on an Olympus fluorescent microscope at 100× magnification (Olympus IX71, Olympus DP71). Bcr-Abl appears in compact clusters in WP1130-treated cells.