GC and neoplasm: Figure 4I shows that gC mRNA was present in the lungs of tumor-bearing mice, with the highest levels on day 1 and decreasing levels on subsequent days. Importantly with respect to specificity and safety, gC mRNA was not detected in the lungs of tumor-negative mice, nor in the liver or brain of mice positive for lung metastases (Figure 4J–L). Accordingly, tumor detection by means of HER2 determination confirmed that the lungs of virus-treated CT26-HER2-positive mice were the only organs harboring significant amounts of tumor nodules (Figure 4M).