NRTN and Parkinson disease: Overexpression of NTN and Lmx1α in rhesus BMSCs has been shown to strongly promote DA neurogenesis in vitro and restore motor function after transplantation in vivo in a PD monkey model, established by treating monkeys with 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridin [4].