APC and cancer: The targeted cancer-driver genes were Apc, whose exon 15 was flanked by loxP sites (Apclox/lox), Kras, which contained a G12D mutation and a transcription termination site flanked by loxP sites upstream of the first coding exon (KrasLSL-G12D/+), and Tp53, whose exons 2–10 were flanked by loxP sites (Tp53lox/lox) (Figure 1a and Figure S1a).