The ErbB4 receptor tyrosine kinase is expressed in hippocampal and dopaminergic neurons and cerebellar granule cells, as well as in glia1, 2, and is upregulated in multiple neurological disorders2-7 with a prominent overexpression observed in neuronal populations of the affected brain areas including peri-injury regions in ischemia4 and brain trauma7, dopaminergic neurons in midbrain of Parkinson's disease patients3, and hippocampal neuritic plaques in Alzheimer's disease5. This evidence concerns the gene ERBB4 and Parkinson disease.