We found that AD DAOs with other neuronal cell types did not increase the number of Mbp+ branches in the presence and absence of SCH772984 treatment (Supplementary Fig. 14b–f), suggesting that inhibition of ERK/MAPK signaling in other neuronal cell types did not contribute to the phenotypic changes in DAOs (Fig. 4d–f). Here, MAPK1 is linked to Alzheimer disease.