In conclusion, by utilizing the novel system for genetic lineage tracing with live imaging, including the use of a dual-recombinase system that combined both flippase-FRT and Cre-loxP recombinations, we for the first time provided direct evidence for the crucial stem cell activity of Dclk1+ tumor cells within primary PDAC and its precursor lesions as well as metastatic lesions in vivo. This evidence concerns the gene DCLK1 and neoplasm.