Soluble forms of NKG2D receptor ligands (MHC class I polypeptide-related sequence A [MICA], MICB, and UL16 binding protein 2 [ULBP-2]), found in elevated concentrations in peritoneal fluid of endometriosis patients, especially in deep infiltrative forms, can bind to NKG2D, causing its internalization and degradation (71). The gene discussed is MICA; the disease is endometriosis.