PDX1 and pancreatic neoplasm: To assess U-13C-glucose labeling of metabolites in autochthonous pancreatic tumors arising in the LSL-KrasG12D; Trp53fl/fl; Pdx1-Cre (KP-/-C) (Bardeesy et al., 2006) and the LSL-KrasG12D; Trp53R172H/+; Pdx1-Cre (KPC) (Hingorani et al., 2005) mouse models, we first confirmed that plasma glucose levels were not changed over the course of the experiment (Figure 1A).