ABCB1 and B-cell chronic lymphocytic leukemia: Currently, ibrutinib, which was approved by Food and Drug Administration (FDA) for treating mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) (Zhang et al., 2017), has been reported to have significant effect to improve the efficacy of chemotherapeutic drugs transported by ABCB1 transporter in ABCB1-overexpressing cells (Zhang et al., 2017).