CDC20 and osteosarcoma: In summary, we propose a model for the regulation of BRD7 by the APC/Ccdh1 and APC/Ccdc20 E3 ligase complex in osteosarcoma (Fig. 7): two activators of the APC/C E3 ligase complex, Cdh1 and Cdc20, bind to BRD7 directly, triggering the degradation of BRD7 and consequently resulting in the loss of BRD7's inhibitory effects on the tumorigenesis of osteosarcoma.