PECAM1 and neoplasm: Furthermore, WFA induced a significant decrease in tumor-associated blood vessels, and small collapsed CD31-positive vessels were detected in the treated tumors (mean±SD microvascular density [MVD] was 38.2±17.1 and 64.3±21.6 in control tumors and 11.4±7.8 and 6.1±5.8 in WFA-treated tumors of SKLMS1 and HT1080 xenografts, respectively; P = 0.021 and P<0.0001).