KLRK1 and glioblastoma: Although ULBP-1 (Figures 4K,O), ULBP-3, and ULBP-2/5/6 stress ligands recognized by NKG2D and B7-H6, CD112 ligand recognized by NKp30, DNAM-1 activating receptors, respectively, were diminished in the serum-cultured 2012-018 GBM cells, inhibitory classical HLA–ABC ligands were markedly upregulated in 2012-018 GBM cells when cultured in serum-containing medium (Table 1).