APLP1 and Alzheimer disease: A highlight of this work has been that APP and APLP1 have been shown to have overlapping functions with APLP2 as double knockouts of APP/APLP2 and APLP1/APLP2 exhibit early prenatal death clearly demonstrating an essential function for these proteins [37,38] and the redundancy of APP and APLP2 function indicates that a down regulation of APP could be a viable treatment for AD as APLP2 could substitute for the vital APP functions without contributing to disease.