Another major molecular mechanism used by tumor cells to impair NK cell recognition and activation is based on the expression of inhibitory (as major histocompatibility complex (MHC) class I molecules) and the release in a soluble form of ligands (such as MHC class I polypeptide–related sequence (MIC) A/B and UL16 binding protein (ULBP1-6) for NK cell-activating receptors [12,13]. Here, NCR1 is linked to neoplasm.