Expression of Ki67 and CD105 in Salivary Gland Tumors

Angiogenesis, development of new blood vessels from previous blood vessels, is necessary for tumor growth and metastasis. During recent years, a lot of effort has been put into identifying markers of angiogenesis (Meng et al., 2012). CD105 is not only a marker that has an important role in angiogenesis (Nassiri et al., 2011) but also it is essential for proliferation of endothelial cells and stimulates active phase of angiogenesis (Goumans et al., 2003). CD105 is a membranous homodimer protein with a molecular weight of 180 KDa, and the gene for this protein is located on chromosome 9 which is expressed on the cell surface (Dallas et al., 2008). There are two isoforms of protein with the capacity of binding to Transforming Growth Factor β (TGF-β) that differ in the cytoplasmic amino acid composition. Most of CD105 functions are likely to be associated with TGF-β signaling , however in some processes it is independent of TGF-β signaling (Levi et al., 2011) . Endothelial cells of blood vessels are the main source of CD105 (Duff et al., 2003). Other cells including vascular smooth muscle cells, fibroblasts, macrophages, can also