MYBL2 and plasma cell myeloma: Circ-MYBL2 was reported to be downregulated in multiple myeloma tissues, which could inhibit the phosphorylation and activation of its host gene encoding protein MYBL2 by promoting the binding of Cyclin F to MYBL2, thereby inhibiting the transcription of some critical proliferation-related oncogenes, and playing a tumor suppressor role [86] (Fig. 4B).