STUB1 and Alzheimer disease: BACE1 is regulated by the E3‐ligase CHIP. CHIP stabilizes APP by promoting the ubiquitination and proteasomal degradation of BACE1, thereby reducing Aβ production BACE1, a key enzyme involved in the production of Aβ in AD, which is regulated by the E3‐ligase CHIP. CHIP stabilizes APP by promoting the ubiquitination and proteasomal degradation of BACE1, thereby reducing Aβ production.