“…Considering that not only the tip-related expression of notum but also the brainrelated expression completely disappears after β-catenin-1 RNAi, notum may be directly regulated by β-catenin-1, generating a regulatory loop to control β-catenin-1 levels in the anterior region of planarians (Hill and Petersen, 2015;Petersen and Reddien, 2011;Scimone et al, 2014). Our findings thus support three major roles of β-catenin-1 in anterior regeneration: (1) the specification and maintenance of the anterior signaling center, defined by the tiprelated expression of notum (Petersen and Reddien, 2011) and other genes (Chen et al, 2013;Gaviño et al, 2013;Roberts-Galbraith and Newmark, 2013;Scimone et al, 2014;Vásquez-Doorman and Petersen, 2014;Vogg et al, 2014) (Fig. 6A,B); (2) the regeneration of the brain, through the regulation of the brain-related expression of notum (Hill and Petersen, 2015); and (3) the specification of different neuronal cell types, as described in most animal models (Ciani and Salinas, 2005;Hari et al, 2002;Lewis et al, 2004;Machon et al, 2003;Watanabe et al, 2014;Yu and Malenka, 2003;Zechner et al, 2003).…”