GPR37 and Parkinson disease: Gpr37<tm1Dgen> null mutants were also instrumental in investigating Gpr37’s neuroprotective action in a specific, dopamine analogue-induced model of PD [32] and further applied to characterize the Gpr37 N-terminal ectodomain as a potential biomarker for PD [33], following its proteolytical cleavage and shedding by a metalloprotease and furin [34].