PECAM1 and neoplasm: On Day 6, whereas ionizing radiations alone had no significant effect on tumor vessel density (40.2+/−14.4 vs 62.5+/−13.3 in the CTRL group), tumors in mice treated with GEF alone had significantly higher CD31-positive vessels (115.3+/−10.5; p = 0.0286) than CTRL, representing approximately a two-fold increase (Fig. 5C).