The gene expression of the extra-cellular ligand SEMA6D, proposed as one of three initiators of the integrated Parkinson's disease mechanism (Figure 7), was found in our miRNA regulatory network to be regulated by seven miRNAs (miR-124-1, miR-128-1, miR-16-1, miR-19a, miR-23b, miR-30a and miR-9). Here, SEMA6D is linked to Parkinson disease.