TP53 and neoplasm: To screen for potential markers indicative of tumor origin, we triggered oncogenic Ras activation and p53 inactivation in duct- and acinar-derived cells in parallel using KPCkY (KRasLSL-G12D/WT; P53F/F; Ck19-CreER; Rosa26-LSL-YFP) and KPEY (KRasLSL-G12D/WT; P53F/F; Ela1-CreERT2; Rosa26-LSL-YFP) mouse strains (Figure 5A).