Intensity of tumor angiogenesis is supposed to be reflected by intratumoral microvessel density (MVD), but it is difficult to assess revascularization by normal microscopy; therefore various antibodies members for endothelial cells have been used to demarcate the area of vascularity within the tumor out of which CD-31 has the best documented specificity for endothelial cells. This evidence concerns the gene PECAM1 and neoplasm.