CCNB1 and neoplasm: However, in the presence of circ‐Ccnb1, the interaction between Ccnb1 and Cdk1 was dissociated, accompanied by the formation of a large complex containing circ‐Ccnb1, Ccnb1 and Cdk1, resulting in inhibited Ccnb1 function as well as suppression of tumour growth [119].