In addition, an in vivo study that used a mouse model of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) demonstrated that KD5040 improves motor function, rescues dopaminergic neurons, and improves the expression level of tropomyosin receptor kinase A (TrkA), which is involved in neuronal differentiation [6]. This evidence concerns the gene NTRK1 and Parkinson disease.