However, pNK-non-sensitive cancer cells (MDA-MB-231and MDA-MB-468) expressed high levels of HLA-C2 (Additional file: Fig. S5d) whereas pNK-sensitive cancer cells (MCF-7) expressed low levels of both HLA-C1 and HLA-C2, indicating the contribution of inhibitory KIR-KIR ligand mismatch in pNK cytotoxicity. Here, KIR3DL1 is linked to cancer.