CD48 and glioblastoma: Regarding ligands corresponding to the inhibitory NK receptors, GBM expressed CD48 (ligand for 2B4) and HLA-E (ligand for CD94/NKG2A) at low levels and HLA-class I (ligand for KIR2DL) at high levels in GBM cell lines (Fig 2E, 2F, 2G and 2H).