LEF1 expression is reported to be involved in leukemic transformation [4], and associated with poor prognosis in adult B precursor acute lymphoblastic leukemia (ALL) [6], chronic lymphocytic leukemia(CLL)[6,7], cytogenetically normal acute myeloid leukemia (AML), and adult de novo acute promyelocytic leukemia (APL)[8]. This evidence concerns the gene LEF1 and acute promyelocytic leukemia.