The molecule, currently known as osteopontin (OPN) was first described in 1979 as a phosphoprotein associated with transformation of epithelial cells. Identification of its role in osteoblasts, in 1986, as a calcium binding protein, enabling formation of bone structure, contributed to it becoming widely known as osteopontin. Osteopontin is overexpressed in various physiological and pathological processes, as for instance: bone remodeling, inflammation, atherosclerosis, vascular injury and renal diseases. Numerous publications suggest that OPN can be a valuable tool in clinical oncology for prognosis of disease deve-lopment and treatment monitoring of a variety of cancers. Recent reports on the role of osteopontin in mechanisms involved in progression of cancer indicate that OPN may be considered as
a potential target for chemotherapy.