Drug combination studies: imatinib and nilotinib against imatinib-resistant, BCR-ABL–expressing cell lines. Proliferation studies showing 3-day treatments of (A) F317L-Ba/F3 cells, (B) M351T-Ba/F3 cells, and (C) F486S-Ba/F3 cells with nilotinib, imatinib, or a combination of nilotinib and imatinib. (D) Proliferation study showing a 2-day treatment of E255K-Ba/F3 cells with nilotinib, imatinib, or a combination of nilotinib and imatinib.