PCP4 (also known as PEP‐19) in particular regulates Ca2+ binding to calmodulin, and the levels of transcript and protein of PEP‐19 are reduced in striatum of the MPTP mouse model of PD.41 In addition, we found higher expression of ATP13A4, cation‐transporting, P5‐type adenosine triphosphatase, among the ventral SNpc neurons. The gene discussed is ATP13A4; the disease is Parkinson disease.