Xing, Ligang, et al. “Non-Invasive Molecular and Functional Imaging of Cytosine Deaminase and Uracil Phosphoribosyltransferase Fused With Red Fluorescence Protein”. Acta Oncologica, vol. 47, no. 7, Jan. 2008, pp. 1211-20, doi:10.1080/02841860802256475.