WT1 and leukemia: Seeing as WT1 has been extensively documented to be involved in the early stages of physiological hematopoiesis, being involved in triggering primitive progenitor lineage differentiation [125], overexpression in leukemias in unsurprising, yet WT1 expression has been documented in tumors which originate from tissue in which WT1 is not physiologically expressed, implying a WT1 oncogene function in these neoplasms.