Some signaling pathways, such as NRG, PRL, NGF, etc. among neurons (Supplementary Figure 10B), and TGFb, TRAIL, LT, etc. between DaN and non-neuronal cells (Figure 4B), have a larger Euclidean distance than other signaling pathways, implying that these pathways are greatly altered in PD compared with control. This evidence concerns the gene PRL and Parkinson disease.