GDNF and Parkinson disease: As one of the major avenues of therapeutic investigation in PD has been the delivery of candidate therapeutic agents, and we previously observed increased production of two such candidates (GDNF and BDNF) by GDAsBMP (Davies et al, 2008, 2011), we first examined whether generation of GDAsBMP from rat GRP cells is associated with the expression of other agents of potential interest in PD treatment (Fig 1A).