Grb10 interacting GYF Protein 2 (GIGYF2), which cooperates with the Grb10 adapter protein to stimulate IGF-1 receptors [22], was identified in dopaminergic neurons in the substantia nigra pars compacta (SNpc) of PD brain tissue and is involved in the regulation of tyrosine kinase receptor signaling at endosomes [23]. Here, GIGYF2 is linked to Parkinson disease.