Given the existence of a background WT1 expression in normal bone marrow, qualitative RT-PCR provided conflicting results on the clinical value of this marker (11, 12), whereas RQ-PCR can be used to assess different levels of WT1 transcripts in AML cells, normal hematopoietic cells and normal bone marrow cells regenerating after chemotherapy (13, 14). Here, WT1 is linked to acute myeloid leukemia.