ABCB1 and myelodysplastic syndrome: In agreement with the present findings, other groups also reported a lack of increased ABCB1 [14,19,20,31], ABCC1, and ABCG2 [31] expression in AZA-resistant cells compared to their parental cells and in bone marrow blasts from AZA-treated MDS patients at the time of relapse [25].