Genetically engineered mouse models (GEMMs) of pancreatic cancer also support a key role of KRAS in PDAC development.100,101 Accordingly, the GEMM that best epitomizes the evolution of human PDAC includes the expression of a mutant Kras (KrasG12D) from the endogenous Kras locus through a Cre recombinase that is under the control of a pancreas-specific promoter, including Ptf1a/p48 (p48) or Pdx-1 [e.g., LSL-KrasG12D; p48-Cre mice, aka the KC model102]. Here, PDX1 is linked to keratoconus.