In the chronic myeloid leukemia (CML) cancer cell lines K562 and LAMA-84 and imatinib-resistant cell cultures, elacridar at a concentration of 0.25 μM was tested in combination with imatinib; the flow cytometry analysis confirmed the successful inhibition of ABC transporter activity, leading to a reversal of imatinib resistance. This evidence concerns the gene ABCG2 and cancer.