PDX1 and pachyonychia congenita: The role of oncogenic Ras in PC was examined by directing endogenous expression of KrasG12D in the progenitor cells of the pancreas in KrasG12D;Pdx1-Cre (KC) mice [3], whereas the role of the endogenous expression of Trp53R172H and KrasG12D was examined in the pancreas of KrasG12D;Trp53R172H;Pdx1-Cre (KPC) mice [4].