APP and neuroblastoma: We increased cellular NAD+ levels by incubating the Aβ (N2s: N2a mouse neuroblastoma cells expressing the Swedish K595N and M596L mutations in Amyloid-beta precursor protein) and tau cells (HEK293 cells Tau P301L) with NAD+ precursor nicotinamide mononucleotide (NMN, 0.5 mM) for 24 h.