Studies have also shown that inhibiting GRP78 mRNA level reduces ERS resistance to 6-OHDA-induced neuronal damage in PD rat models, and downregulation of GRP78 hinders the activity of the proapoptotic factor caspase-3, thereby improving rotenone-induced neuronal damage in the PD rat model [27, 28]. This evidence concerns the gene HSPA5 and Parkinson disease.