PDX1 and pancreatic neoplasm: Direct analysis of pancreatic tumor tissue from Pdx1-Cre;LSL-KrasG12D/+;Trp53fl/+ and Pdx1-Cre;LSL-KrasG12D/+;LSL-Trp53R172H/+ mice showed that tumors had increased Ido1 expression versus normal pancreas tissue, and that certain tumors expressed high levels of Ido1 (Figures 1B and 1C).