To dissect the molecular mechanisms of acquired resistance to inhibitors of the TK pathway, we generated drug-resistant derivatives of leukemia cells K562 (BCR::ABL1), MV4-11 (FLT3), and Kasumi-1 (c-KIT) by long-term culture in the presence of TKIs nilotinib (second generation) or imatinib (first generation) (10, 30, 100, 300, 1,000 nM). The gene discussed is KIT; the disease is leukemia.