PECAM1 and neoplasm: Similar to gene expression results, we observed that CD31, VEGF and bFGF protein levels expression started at the early stage when the volume of the tumor is less than 100 mm.3 The results of mean MVD of CD31 showed that its expression is raised in a consistently form in compare to VEGF which is increased in the early stage and climbed sharply in the advanced stage and then went up moderately.