PTPRZ1 and glioblastoma: We immunohistochemically analyzed a series of gliomas (oligodendroglioma, IDH mutant and 1p/19q-codeleted, WHO grade 3; astrocytoma, IDH mutant, WHO grade 3; and glioblastoma, mot otherwise specified, WHO grade 4) to verify the expression of GnT-IX and PTPRZ with the HNK-1 epitope (Fig. 4A).