PECAM1 and neoplasm: To explore further the potential mechanism of antitumor activity of Ad.5-TCTV and whether this effect involves induction of apoptosis in tumors and inhibited angiogenesis in vivo, tumor sections were evaluated using immunohistochemical assays (IHC) to determine the levels of MDA-7/IL-24, adenovirus E1A, Luciferase, CD-31, Bcl-2, and GRP-78 proteins (Figure 7A,B).