Later, other groups validated the concept by generating TrkB small molecule agonists and TrkB and TrkC agonistic mAbs that were protective in the MPTP neurotoxicity mouse model of PD (Berezov et al., 2002; Jang et al., 2010; Devi and Ohno, 2012; Bollen et al., 2013; Coles et al., 2014; Chitranshi et al., 2015; Nie et al., 2015), HD (Jiang et al., 2013; Simmons et al., 2013), and ALS. The gene discussed is NTRK2; the disease is Parkinson disease.