Fig. 2

Simplified schematic of Hedgehog signaling. a In the absence of HH (hedgehog), the ligand PTCH1 (PATCHED) inhibits SMO (SMOOTHENED) and prevents SMO from translocating to primary cilia. In the absence of SMO, GLI (glioma-associated oncogene) transcription factors are enzymatically processed into their repressor form and act to negatively regulate canonical Hh-controlled genes. b In the presence of Hh signaling, the inhibition of SMO by PTCH1 is relieved, allowing SMO to translocate to primary cilia. SMO translocation to primary cilia allows the enzymatic processing of GLI transcription factors into their active form, allowing them to activate Hh-controlled gene expression