In vivo imaging of an inducible oncogenic tumor antigen visualizes tumor progression and predicts CTL tolerance.

Visualizing oncogene/tumor Ag expression by noninvasive imaging is of great interest for understanding processes of tumor development and therapy. We established transgenic (Tg) mice conditionally expressing a fusion protein of the SV40 large T Ag and luciferase (TagLuc) that allows monitoring of oncogene/tumor Ag expression by bioluminescent imaging upon Cre recombinase-mediated activation. Independent of Cre-mediated recombination, the TagLuc gene was expressed at low levels in different tissues, probably due to the leakiness of the stop cassette.