PECAM1 and neoplasm: The mean (SD) CD31- microvessel density (MVD) in the tumor specimens was 22.3 (13.02) in control DLD-1 xenografts, 40.0 (16.9) in erythropoietin treatment DLD-1 xenografts, 2.0 (3.5) in control Ht-29 xenografts and 2.3 (6.3) in Ht-29 xenografts receiving erythropoietin.