Provided herein are bifunctional compounds with a moiety (e.g., lenalidomide, thalidomide) that is a binder of an E3 ubiquitin ligase (e.g., Cereblon) and another moiety (e.g., RA190) that is a binder of the ubiquitin receptor RPN13 to induce degradation of RPN13 and thereby inhibit proteasome function. Also provided are pharmaceutical compositions comprising the bifunctional compounds, and methods of treating and/or preventing diseases (e.g., proliferative diseases, cancers, benign neoplasms, pathological angiogenesis, inflammatory diseases, and autoimmune diseases). Provided also are methods of inducing the degradation of ubiquitin receptor RPN13 by administering a bifunctional compound or composition described herein, wherein one component of the bifunctional compound is a binder of an E3 ubiquitin ligase (e.g., lenalidomide, thalidomide) and another component of the compound is a binder of ubiquitin receptor RPN13 (e.g., RA190) in a subject.
