To determine differential expression of ROBO4 in this kidney cancer model, and to provide a backdrop for our investigation of the human ROBO4 enhancer/promoter fragment used in our Ad5ROBO4-EGFP vector, we tested ROBO4 protein levels in 786-O orthotopic (KO) and subcutaneous (SC) tumors compared to liver using a validated ROBO4 antibody (Figure 1) [25], [26]. This evidence concerns the gene ROBO4 and kidney cancer.