CALB2 and Parkinson disease: Hence, the increase of Calb2 in myenteric cultures might be a first reaction to A30P α-synuclein, while a reduction of Calb2 expression, as seen in whole-mount stainings of psA30P mice, resembles later stages of PD and chronic exposure to pathological A30P α-synuclein, where augmented cell death has already occurred.