In addition, Zhao et al.’s study demonstrated that quercetin improved the blood-brain barrier dysfunction by increasing the expression of ZO-1, Claudin-5, β-catenin, and LEF1, and decreasing the expression of MMP-9, GSK-3β and Axin in cerebral ischemia reperfusion model [52]. The gene discussed is GSK3B; the disease is brain ischemia.