Drug resistance mediated by CRBN depletion is specific for IMiDs, not for other unrelated antimyeloma compounds. OPM2 cells stably expressing either NT or CRBN shRNA were seeded and incubated with lenalidomide (A), pomalidomide (B), and other antimyeloma drugs, including bortezomib (C), dexamethasone (D), and melphalan (E) at the indicated concentration, followed by MTT assay at day 3 after adding drugs. Each experimental condition was performed in triplicate and repeated at least once.