SIX1 and Nephroblastoma: Genes identified as targets of wild-type SIX1 in both Wilms tumor and hFK but not of SIX1-Q177R include established NPC-enriched genes FOXC1 and TMEM100, both of which were also found to be upregulated in SIX1/2-Q177R tumors (Figs 4A and 1C).