PTPRZ1 and central nervous system cancer: Among the sialoglycoproteins overexpressed in GBM cells identified in this study, we found well-known proteins reported to be involved in various aspects of glioma biology (e.g., PTPRZ1, GPR56, TNC, IL13RA2, ICAM1, NCAM1, THBD and NTRK2) as well as some specific glioma-associated cell surface antigens or receptors that are targets for cytotoxic and targeted agents currently under clinical trials for glioblastoma (PTPRZ1, IL13RA2, TNC and TFRC) [5].