SHH and Parkinson disease: Smo cKO in striatal cholinergic INs or Shh cKO in young mDA neurons resulted in the progressive worsening of LIDs despite the lack of an mDA phenotype in these mice, whereas the OE of a constitutively active SMO protein in a genetic PD mouse model blocked the appearance and intensification of LIDs despite the severe mDA phenotype of these animals (Malave et al., 2021).