GDNF and Parkinson disease: We further found that GDAsBMP produced elevated levels of brain-derived neurotrophic factor (BDNF) and glial-derived neurotrophic factor (GDNF), two neurotrophic factors of particular interest as potential interventions for therapy of PD (Altar et al, 1992; Sauer et al, 1994; Yurek et al, 1996; Rosenblad et al, 1999; Kirik et al, 2001; Wang et al, 2002; Ben-Hur et al, 2004; Sun et al, 2005; Saylor et al, 2006).