SNAP25 (Synaptosomal associated pr otein of 25 kDa) is a presynaptic plasma membrane protein that is widely distributed throughout the brain and involved in the regulation of neurotransmitter release. Decreased levels of SNAP25 have been found in the brains of patients with Down Syndrome and Alzheimer's Disease (Greber et al., 1999). In addition, a significant reduction in the hippocampal expression of SNAP25 has also been found in patients with Schizophrenia (Fatemi et al., 2001). Increasing evidence suggests that SNAP-25 also modulates various ion channels, including voltage gated calcium channels (VGCCs) (Pozzi el al., 2008). Activation of PKC results in the phosphorylation of SNAP-25 on ser187 (Shu et al ., 2008). Phosphorylation of SNAP25 on ser187 is believed to cause inhibition of VGCC (Pozzi el al., 2008). Since ser187 phosphorylation is transiently induced by neuronal activity, SNAP25 creates a negative feedback mechanism for controlling neuronal excitability (Pozzi el al., 2008).