To better understand glucose metabolism of PDAC tumor tissue in vivo, we infused U-13C-glucose into conscious, unrestrained mice (Davidson et al., 2016; Hui et al., 2017; Marin-Valencia et al., 2012) bearing PDAC tumors from autochthonous models that are driven by activating mutations in Kras and disruption of Trp53 function (Bardeesy et al., 2006; Hingorani et al., 2005). This evidence concerns the gene TP53 and neoplasm.