Paprocka M, et al. – Aim was to elucidate MRP1 protein expression in leukemic stem cells (LSC) as a negative prognostic marker in acute myeloid leukemia (AML) patients. For the first time, the high negative correlation between MRP1 protein expression in LSC and AML patients’ remission was presented. These findings highlighted MRP1 expression in LSC as an adverse prognostic marker in patients with de novo AML.