Given that mTOR is a downstream target of the Akt and Erk 1/2 pathways as previously mentioned, and VEGF-B has been shown to upregulate these pathways in a PD model system [19], it is possible that VEGF-B's protective effects involve mTOR downstream of increased Akt and Erk, reducing apoptosis and protecting neurons from injury (Figure 1). Here, AKT1 is linked to Parkinson disease.