To further confirm whether ERS was activated in the brain of 2 × Tg-AD mice and the effect of ECH on it, we next assessed the level of glucose-regulated protein 78 (GRP78) by Western blot because GRP78 is the earliest marker of ERS and appears to be the most sensitive in 2 × Tg-AD mice (Ron and Walter, 2007). The gene discussed is HSPA5; the disease is Alzheimer disease.