Although genetic loss of the p53 tumor suppressor has been associated with metastasis in PDA, a direct comparison of mice bearing mutant p53R172H (Pdx1-Cre;LSL-KrasG12D;p53R172H/+) to conditional deletion of p53 (Pdx1-Cre;LSL-KrasG12D;p53flox/flox) revealed that metastasis was observed only in p53R172H mutant-expressing PDA [122], suggesting that the R172H mutation is a p53-gain of function mutation that promotes PDA metastasis. The gene discussed is PDX1; the disease is Patent ductus arteriosus.