Finally, Gorczynski and colleagues showed that tumor growth in vivo can be monitored by levels of soluble CD200 in serum of tumor-bearing animals [21], whereas Moreaux and colleagues found significant overexpression of CD200 in a variety of cancers compared with normal cells or tissues and suggested that CD200 might be a potential therapeutic target and prognostic factor for a large array of malignancies [22]. Here, CD200 is linked to cancer.