CCNB1 and breast carcinoma: Meanwhile, Circ-Ccnb1 was found to bind to both Ccnb1 and Cdk1 proteins to dissociate the formation of the Ccnb1-Cdk1 complex and inhibit the tumor-promoting function of its host gene Ccnb1 by forming a large complex containing circ-Ccnb1, Ccnb1 and Cdk1, thereby inhibiting breast cancer cell proliferation, migration, invasion and tumor growth in vivo [83].