 APLP2/APP double knock out mice and APLP2/APLP1 double knock out mice each show a lethal phenotype (postnatal day 1), whereas APLP1/APP double knock out mice are apparently normal, demonstrating the importance of the APLP2 protein.APLP2 plays a role in synaptic plasticity, functioning to promote neurite outgrowth, neural cell migration and copper homeostasis.Analysing the neurons and networks of APP/APLP2 double knock out mice using stem cell-derived neurons and slice cultures, shows deficient excitatory synaptic transmission in this genotype.