Therefore, based on promoter-reporter gene strategy, we have devised and constructed the lentivirus vector of pLV-PNanog-GFP-T2A-Luc harboring GFP and luciferase (Luc) under control of human Nanog promoter (Fig. 3A), which allows us to integrate respective advantages of fluorescence and bioluminescence imaging to visualize putative CSCs within in vitro cultured cancer cells and in vivo optically image and quantify a rare population of putative CSCs in human tumor xenograft-bearing mice. Here, NANOG is linked to cancer.