Multidrug resistance-associated protein 1 (MRP1) expression level in acute myelogenous leukemia (AML) and acute lymphoblastic leukemia (ALL) samples. Expression of MRP1 in the nonresponse (NR) group (phase i) compared with normal, complete remission (CR) and early relapsed groups (phase j). In ALL samples, no significant difference was observed. In contrast, in AML samples from relapsed and NR groups, the MRP1 level is significantly different from the healthy and CR groups (p-value = 0.001), but the mean difference between the NR and Relapsed patients is nonsignificant (p-value = 0.171). This evidence concerns the gene ABCC1 and acute lymphoblastic leukemia.