TH and Parkinson disease: Emerging evidence reveals that TH is ubiquitinated in PD, which results in its degradation by the ubiquitin–proteasome system.[10, 11, 12] Importantly, pathological TH is a potential source and contributor to the generation of reactive oxygen species (ROS), which is a common feature of many neurodegenerative disorders, including PD.[13, 14] Thus, TH may be a promising candidate target protein for developing new treatments of PD,[15] though the potential of targeting TH ubiquitination has not been extensively researched.