APC and cancer: Another E3 ubiquitin ligase complex APC/C mediates irradiation-induced degradation of cyclin D1 via its subunit Cdc27/APC3.20,21 It is noteworthy that the expression of Cdc27/APC3 is repressed in many types of cancer cells, but whether Cdc27/APC3 dysregulation promotes tumorigenesis via cyclin D1 is not reported.