Inhibition of autophosphorylation in Bcr-Abl–mutant, nilotinib-resistant cell lines. Mutations that emerged in the nilotinib screen were reengineered and expressed in Ba/F3 cells. Cells were incubated without and in the presence of nilotinib at the indicated concentrations. Cell lysates were subjected to SDS-PAGE. Blots were probed for phosphotyrosine (left) and Abl (right). (A) Results for resistance mutations displaying cellular IC₅₀ values of less than 500 nM and (B) for mutants causing strong resistance toward nilotinib with cellular IC₅₀ values of 500 nM or above.