In addition, a soluble form of CD200 (sCD200), released following CD200 ectodomain shedding by matrix metalloproteinase-1 (MMP1) and ADAM19 metallopeptidase, is able to engage CD200R1, can be quantified in the serum, and has been correlated with worse tumor prognosis in CLL (25) and GBM patients (20). The gene discussed is CD200; the disease is glioblastoma.