PTCH1 and embryonal rhabdomyosarcoma: However, sporadic ERMS lack canonical HH signaling activity via the HH/PTCH/SMO/GLI axis [26, 27] and GLI activity is apparently regulated in a non-canonical manner, which summarizes the regulation of GLI transcription factors by interaction with other signaling pathways including the RAS pathway (reviewed by e.g., refs. [24, 28].