In order to track the transplanted cancer cells in vivo using imaging analysis, 4T1 cells were transduced with a self-inactivating lentiviral vector carrying a ubiquitin promoter driving firefly luciferase (Fluc) and enhanced green fluorescence protein (eGFP) followed by a seven-repeat Stat3-binding sequence (enhancer) and minimal TA (promoter) driving renilla luciferase (Rluc) reporter genes (4T1-Fluc/GFP-pStat3/Rluc). This evidence concerns the gene STAT3 and cancer.