In the KPC mice we used in this study (Figure 5, E–G), Cre recombination induces heterozygous deletion of p53 gene, and complete loss of its tumor suppressor activity relies on a spontaneous second-hit mutation on the wild-type allele (a great majority of these mutations are expected to be loss of heterozygosity), which is sufficient to induce PDAC at 100% penetrance but insufficient to promote metastasis. Here, TP53 is linked to neoplasm.