Activating ligands include non-peptide substances such as phosphoantigens (PAgs) [79], aminobisphosphonates [80] and alkylamines [81,82] as metabolites of the mevalonate pathway upregulated in cancer cells [83], as well as MHC class I polypeptide-related sequence A/B (MICA/MICB) [75,84], heat shock proteins [85], butyrophilins/butyrophilin-like (BTN/BTNL) molecules [20,21] and members of unique long 16 (UL-16)-binding proteins (ULBP/RAET1) [86,87]. The gene discussed is MICA; the disease is cancer.