These works allowed Barry Hoffer and, later, Anders Björklund and their colleagues to initiate cell transplantation experiments as well as to use GDNF as the first NTF to restore dopamine neurons in animal models of Parkinson’s disease (Hoffer et al., 1994; Sauer et al., 1995; Winkler et al., 1996). The gene discussed is GDNF; the disease is Parkinson disease.