Luciferase expression driven by MUC4-oncotropic virus co-localizes with fluorescence in tdTomato-MIAPACA2 tumors. (A) MIAPACA2 cells were modified to express permanently the tdTomato reporter gene, detectable with the photon imager in subcutaneously grafted tumors (top panel). Lentiviruses carrying the luciferase reporter gene combined with anti-MUC4, anti-CLDN18 (PDAC targeting antibodies), rabbit IgGs (ISO, negative control for the targeted gene transfer) or packaged into the broad tropism VSV-G-containing envelope (positive control) were directly injected in the tumors (n = 3 in each group). Three weeks after virus injections luciferase signal was measured in anesthetized live animals with a photon imager apparatus (bottom panel) and co-localizes only with fluorescent tumor cells. (B) Quantification of luminescence in ph/sr/s was divided by tumor fluorescence (ph/sr/s) and is expressed as a percentage of VSV-G positive control. Student’s t tests against the VSV-G condition were statistically different only for ISO CLDN18 (p = 0.05 for both). Red circles depict the zones used for quantification (same size for all the mice).