ABCC1 and leukemia: In this study, we aimed to investigate the expression of MRP1 in leukemia patients at transcription level and examined whether the messenger RNA (mRNA) level of MRP1 was higher in relapsed patients who were still responsive to drugs (Relapsed) and relapsed patients who presented no response to drugs (NR), compared to control groups (patients at complete remission, CR) and also to healthy individuals.