CD105 is a homodimeric cell membrane glycoprotein linked by disulfide bonds. It is a new class of cell adhesion molecules and plays an important role in regulating angiogenesis. As a receptor of TGF-beta, CD105 is highly expressed in vascular endothelial cells of tumor related neovascular endothelium. Therefore, the evaluation of tumor microvessel density by immunohistochemical staining is significantly correlated with tumor invasion and prognosis.