In particular, Martínez-Pinilla et al. have evaluated the striatal expression of heteromers consisting of GPR55 and CB1/CB2 receptors in parkinsonian macaques, with and without LID, and controls, with the aim to discover whether Parkinsonism correlates with altered expression of the heteromers CB1-GPR55_Hets and/or CB2-GPR55_Hets [77]. This evidence concerns the gene CNR2 and Parkinson disease.