PECAM1 and central nervous system cancer: To visualize tumor cells in the brain, we implanted citrine-expressing mouse glioma cells (GL26-Cit-NT or GL26-Cit-sh2CXCR4) into the striatum of NSG mice (N=5/group) and then labeled the tumor-associated blood vessels with anti-CD31 (anti-PECAM-1)-antibody.