GRK6 and Parkinson disease: Of various post-translational modifications α-Syn can undergo, serine-129 (S129) phosphorylation is considered as a defining hallmark of PD and other synucleinopathies.68,69 In the post-mortem PD patient brains, > 90% of the α-Syn aggregates are known to be S129 phosphorylated, but its functional significance is not yet completely elucidated.70 Many kinases can promote S129 phosphorylation of α-Syn, and overexpression of GRK2 and GRK6 in Drosophila71 and rodent PD models72 showed enhanced and accelerated neuronal death.