Because (1) increased CD105 expression was not only on endothelial cells in tumor neovessels, but also on HSECs and septal fibroblasts in non-tumor tissues; (2) CD105 immunoreactivity was mostly restricted to the endothelium of draining veins; (3) CD105 is a cell surface antigen widely expressed on vascular endothelium, syncytiotrophoblast, some tissue macrophages, and progenitor cells [41]. Here, CD53 is linked to neoplasm.