Fig. 1

Hedgehog signaling pathway in vertebrates. a In the absence of Hh ligand, Ptch inhibits the cilia translocation and activation of Smo. The Gli-Sufu-Kif7 complex forms, and the full-length Gli is subsequently phosphorylated by PKA, GSK3β and CK1 to become GliR with truncated form. The GliR enters the nucleus to inhibit the transcription of Hh target genes. b The binding of Hh-Ptch releases the inhibition of Smo. Activated Smo promotes Gli to escape from the bondage of Sufu and free to become GliA in a full-length form, entering the nucleus to induce target gene expression