USP14 and plasma cell myeloma: The USP14/ubiquitin C-terminal hydrolase L5 (UCHL5) inhibitor VLX1570 was reported to inhibit multiple myeloma (MM) progression in vivo [145]; unfortunately, a phase I/II clinical trial (NCT02372240) evaluating the safety and efficacy of VLX1570 and dexamethasone in patients with refractory MM was terminated due to intolerable toxicity [146].