Primer set of 4a-F and Ex6-R for Ex4a(+) WT1 amplification and Ex6-F and Ex7-R primer pair for whole WT1 amplification were utilized, respectively. The expression levels of WT1 mRNA had been calculated making use of the comparative Ct method (2-Ct) with Actin given that the reference gene. Primer sequences for qPCR are as follows: 4a-F, 5'-ATTCCATTGCCTTTC CACAG-3'; Ex6-R, 5'-GACACCGTGCGTGTGTATTC-3