PTCH1 and basal cell carcinoma: Shh signaling, driven exclusively by PTCH1 that is SMO/GLI1-independent, includes induction of apoptosis in endothelial and neuroepithelial cells (Chinchilla et al., 2010) and regulation of the Cyclin B1/CDK1 pathway in basal cell carcinoma (Wang et al., 2011).