wˌɛn ˌɛsˌeɪtʃˈeɪtʃ ɪz nˌɑːt ˈæktɪv, pˌiːtˌiːsˌiːˈeɪtʃ wˈʌn ɪz ɹᵻspˈɑːnsᵻbəl fɔːɹ səpɹˈɛsɪŋ ðə pˈæθweɪ θɹuː ðɪ ɪnhɪbˈɪʃən ʌv smˈoʊ.
When Shh is not active, Ptch1 is responsible for suppressing the pathway through the inhibition of Smo.