Using fluorescent reporter gene markers to detect the growth, migration labelled cells in living organisms is applied in many kinds of diseases in vivo.30 Here, we used this technology to monitor the location of 4T1 tumour, and the results suggested that fluorescence imaging of 4T1 tumours in both TLR5 knock‐down and negative control virus transfection was much clearer than no virus transfected 4T1 tumour, and with advantage for clearly tumour edge displaying. The gene discussed is TLR5; the disease is neoplasm.