A majority of neurodegenerative diseases are characterized as cholesterol metabolism or storage disorders. Recently, the drug Efavirenz was implicated as a mediator of cholesterol-induced pathology in AD SC- based models. It restores function of MAP, tau, by mitigating cholesterol’s disruption of the UPS, which facilitates tau proteostasis. In this study, we are investigating the mechanistic target of cholesterol leading to UPS dysfunction. We are using human SC-derived neurons to model UPS dysfunction at different regulatory levels and determine which stages can be rescued with Efavirenz treatment. We will use this drug to aid in the complete characterization of cholesterol-mediated tauopathy.