Additionally, we discovered that the large soluble domain of APP (sAPP) enhances tau cleavage by a specific cathepsin, CTSG, in vitro.<h4>Conclusions</h4>Collectively, these results underscore the importance of lysosomal processing of APP, identify a link between APP and tau, and suggest new avenues for exploring AD pathogenesis. The gene discussed is MAPT; the disease is Alzheimer disease.