KRAS and cancer: To examine whether tissue of origin influences the metabolic makeup of the tumor microenvironment, cancer cells derived from lung (Jackson et al., 2005; Jackson et al., 2001) and PDAC (Bardeesy et al., 2006) tumors both driven by activation of Kras and loss of Trp53 were injected subcutaneously into C57BL/6J mice, such that tumors were established in the same location and with the same oncogenic driver mutations, but different tissues of origin (Figure 5A).