WT1 and cancer: Wilms’ tumor gene 1 (WT1), which was originally discovered as a protooncogene, is currently known to be expressed in many tumors [3, 4], and the product of the gene—WT1 protein—is a promising tumor-associated antigen (TAA) that was ranked 1st among 75 cancer antigens [5] and is considered as stem cell antigen [6].