PDX1 and pancreatic neoplasm: Palb2flox/flox;Pdx1-Cre, Brca1flox/flox;Pdx1-Cre and Brca2flox/flox;Pdx1-Cre animals did not develop pancreatic cancer during the lifespans of these mouse strains, which could be because these mice still express the “floxed” conditional allele.