These results suggest impairment of efflux transport in AD cells and were further supported by an observation of decreased P-gp and BCRP expression in AD2-BECs as compared to fControl (P-gp: p = 0.0203, BCRP: p = 0.0372), but not for MRP1 (p = 0.2583). This evidence concerns the gene ABCG2 and Alzheimer disease.