APC and schwannoma: Constitutive activation of β-catenin signaling by knocking down APC using an siRNA in HEI-193 human schwannoma (Fraenzer et al., 2003) and IPN 02.3 Schwann (Li et al., 2016) cell lines resulted in a significant decrease of FOXD3 mRNA level compared with control scrambled siRNA (siScr) transfected cells (Fig. 7A,C).