The degree of neovascularization, or MVD, is now generally identified by immunohistochemical staining of endothelial cells with the so-called pan-endothelial cell markers such as CD34, CD31, and von Willebrand factor; however, anti-pan-endothelial antibodies can react with not only newly formed vessels but also normal vessels trapped within tumor tissues. This evidence concerns the gene PECAM1 and neoplasm.