APC and cancer: In mice, the Tet-On/Off system has been most widely exploited in the field of cancer research in which oncogenes, such as MYC, RAS or BCL2, have been overexpressed as conditional transgenes35–38 or tumour suppressors, such as p53, PTEN or adenomatous polyposis coli (APC), were silenced by RNAi in a regulated manner.