HMOX1 and Alzheimer disease: Compared with the AD model group, the protein expression of Sirtuin1 (Figures 7(a) and 7(d)), total Nrf2 (Figures 7(c) and 7(d)), and nuclear Nrf2 (Figures 7(e) and 7(f)) in PC12 cells in the quercetin group was significantly decreased (P < 0.05), while the protein expression of HO-1 (Figures 7(b) and 7(d)) was increased in the quercetin group (P < 0.05).