MICA and neoplasm: Several tumor immune escape mechanisms have been discovered: up-regulation of HLA class I molecules in myeloma disease; down-regulation of the NKG2D ligands, such as HLA class I chain-related proteins A and B (MICA/B) and unique long 16 (UL16) binding proteins 1–6 (ULBP1-6) in hematological tumors, and down-regulation of activating NK cell receptors due to the release of suppressor cytokines, including transforming growth factor-β (TGF-β) [68].