MYCN and neoplasm: The above findings suggest that DKK proteins may play a role in neuroblastoma pathogenesis, therefore it would be interesting to assess tumor formation in TH-MYCN transgenic mice deficient in DKK3 or DKK1. Certainly, the Wnt pathway is involved in early formation of the neural crest and the subsequent development, migration, and terminal differentiation of neural crest cells (Barembaum and Bronner-Fraser, 2005; Ille and Sommer, 2005), and Wnt/β-catenin signaling has been shown to directly induce MYCN expression (Kuwahara et al., 2010).