May play a role in tumor angiogenesis. Expressed in tumor endothelial cells but absent or barely detectable in normal endothelial cells. Expressed in metastatic lesions of the liver and during angiogenesis of corpus luteum formation and wound healing. Expressed in vascular endothelial cells of malignant tumors but not in normal blood vessels. Expressed in stromal fibroblasts. O-glycosylated with sialylated oligosaccharides. May be N-glycosylated. Endosialin