The expression of activating NK ligands, including MHC class I-related chain A/B (MICA/B) and UL16 binding protein (ULBP), was positive on B2M alteration-induced MHC class I-deficient melanoma cells (30), and the coculture of these cells with NK cells found that they were efficiently killed by NK cells compared with MHC class I-positive melanoma cells (40). Here, B2M is linked to melanoma.