ABL1 and Parkinson disease: The emergence of misfolded α‐synuclein in the substantia nigra as a result of oxidative/nitrosative stress, protein mutation, impaired clearance, and/or genetic factors leads to internalization of misfolded α‐synuclein, which activates the non‐receptor Abelson tyrosine kinase (c‐Abl), a key event in the initiation and progression of neurodegeneration in Parkinson's disease.