In the adult, Shh plays a crucial role in guiding the differentiation oftissue-specific stem cells (Jaks et al.,2008; Shin et al., 2011; Arwert et al., 2012), and inappropriateactivation of Shh signaling could be the culprit that underlines neoplastic growthin the gut epithelium (Nielsen et al.,2004) or lead to outright cancers (Scalesand de Sauvage, 2009; Stecca and Ruiz,2010; Northcott et al.,2012). This evidence concerns the gene SHH and cancer.