CRBN and plasma cell myeloma: Our group, Ben Ebert’s group, and a group at Celgene Corp. went on to show that the cereblon ubiquitin ligase, once bound to an IMiD, acquires the ability to polyubiquitylate, and hence earmark for destruction, the IKZF1 and IKZF3 transcription factors, which play critical roles in myeloma maintenance (128–130).