Given that ventral SN DA neurons are more susceptible to PD-related neurodegeneration compared to dorsal DA neurons [17], we used SLC18A2 and CALB1 to label dorsal DA neurons, and SLC18A2, SOX6, and AGTR1 to label ventral DA neurons, thereby dividing the neurons into three distinct cell subtypes: CALB1+ DA neurons, SOX6+AGTR1+ DA neurons, and non-DA neurons (Figure S2G; Figure 5H, right). Here, SOX6 is linked to Parkinson disease.