Dopaminergic neurons are selectively vulnerable to MPP+ because DA neurons exhibit dopamine reuptake which is mediated by DAT which also has high-affinity for MPP+. The dopamine transporter scavenges for excessive dopamine at the synaptic spaces and transports them back into the cell. Even though this property is exhibited by both VTA and SNc neurons, VTA neurons are protective against MPP+ insult due to the expression of calbindin. Calbindin regulates the availability of Ca2+ within the cell, which is not the case in SNc neurons due to their high-calcium dependent autonomous pacemaker activity.