We then drew the Protein–Protein Interaction (PPI) network map of all differentially expressed synapse‐related proteins and phosphopeptides caused by APOE4 compared to APOE3 in AD mice in order to uncover the molecular basis of APOE4‐induced synaptic degeneration at the presymptomatic stage of AD (Figure 5I). The gene discussed is APOE; the disease is Alzheimer disease.