Here, to explore the mechanisms involved, we carried out an IPA Upstream Regulator Analysis, which identified the pathway “Microtubule-Associated Protein Tau” as a significant upstream regulator in the Npc1−/− cerebellum (Figure 13A), and the pathway was further activated in both brain regions in the Npc1−/−/App−/− mice, suggesting that early-stage tau dysregulation may contribute to NPC pathogenesis. The gene discussed is APP; the disease is nasopharyngeal carcinoma.