WT1 and neoplasm: Our previous studies enforced overexpression of Lin28a or LIN28B from a variety of kidney specific promoters, including Foxd1, Six2 and Cdh16, with no tumor formation, however, overexpression of LIN28B driven via a Wt1 promoter surprisingly showed overt expansion of a Six2-expressing blastema, reminiscent of Wilms tumor33.