APP and neuroblastoma: We confirmed that APP was modified with bisecting GlcNAc in C17 neuroblastoma cells (Akasaka-Manya et al, 2008), while APP in the brain was not reactive with E4-PHA (Supplementary Fig S1F), suggesting that modification of APP with bisecting GlcNAc occurs in a limited number of cell types (Kitazume et al, 2010) and is non-existent or negligible in the brain.