The expression of NGF, abundantly present in the human SN, experiences a marked decrease in both PD patients and PD animal models.[62] However, the utilization of NGF in treating neurodegenerative conditions remains restricted due to associated side effects such as pain and weight loss.[63] In contrast, Rg3 facilitates the formation of the TRKA–GRB2 complex, allowing signal transduction to activate ERK independently of NGF (Figure S7c–f, Supporting Information). This evidence concerns the gene GRB2 and Parkinson disease.