For example, LEF1 expression has been found to be associated with poor prognosis in adult precursor B-cell acute lymphoblastic leukemia and chronic lymphocytic leukemia [14,16,17], while overexpression of LEF1 has been determined as a favorable prognostic factor in childhood ALL and acute myeloid leukemia [13,18,19,20]. This evidence concerns the gene LEF1 and B-cell acute lymphoblastic leukemia.