Suppression of APP-BP1 protein expression by APP-BP1 siRNAs in primary neurons resulted in increases of intracellular Aβ42. Intracellular (from 50 μg of protein from lysates) and secreted (from 1/15 volume of conditioned medium) Aβ42 in primary neurons were determined by Aβ42 ELISA (A). Intracellular (from 50 μg of protein) and secreted (from 1/30 volume of medium of conditioned medium) Aβ40 in primary neurons was determined by Aβ40 ELISA (B). The amount of Aβ in samples that expressed APP without any siRNA interference was used as 100% of Aβ production. All the rest of the samples were normalized to this sample, and presented as percentage in respective experimental conditions. Data is representative of three independent experiments. BP1siRNA, APP-BP1 siRNA; NegsiRNA, Negative siRNA (Stratagene).