CD34 and neoplasm: U-87 MG tumors were significantly more vascularized compared with size-matched tumors generated from Clone #1 cells, as observed by gross examination of the tumors after flipping the skin, by analysis of CD34 positively-stained cells and by presence of blood vessels in H&E staining (marked with arrows) in the U-87 tumor sections (Fig. 4A–4B and Fig. S2).