IGF2 and Nephroblastoma: Moreover, a study using mice in which Wilms tumor-associated mutations – including loss of Wt1 with concurrent stabilization of β-catenin, or loss of Wt1 with concurrent biallelic expression of Igf2 – had been introduced specifically in stromal or NPC lineages demonstrated that these mutation combinations only result in tumor formation within the NPC lineage, further supporting the nephrogenic origin of these tumors (Huang et al., 2016).