PECAM1 and neoplasm: Further, in vivo experiments showed that the tumor size and weight were increased in nude mice injected with GSCs transfected with miR-26a agomir and decreased with miR-26a antagomir, while the angiogenesis endothelial marker CD31 was elevated in the case of miR-26a overexpression, suggesting a role of this miRNA in angiogenesis and tumor growth promotion.