CD200 and glioblastoma: High levels of CD200 have been found to be expressed on various types of cancer cells, including some B-cell malignancies such as hairy cell leukemia, chronic lymphocytic leukemia (CLL), and multiple myeloma (MM), but also malignant melanoma, colon carcinoma, glioblastoma (GBM), and pancreatic ductal adenocarcinoma (PDAC), and were generally correlated with poor patient prognosis (21–24).