RAET1E2, a Soluble Isoform of the UL16-binding Protein RAET1E Produced by Tumor Cells, Inhibits NKG2D-mediated

genes), a family of ligandsfor NKG2D in humans, are frequently expressed by tumor cellsandmediatecytotoxicitiesofnaturalkiller(NK)cellsandCD8AlthoughitremainsunclearwhetherNKG2Dcandirectlyacti-Tcellstotumorcells.ULBP1,ULBP2,ULBP3,andRAET1Llink to membrane through glycosylphosphatidylinositol,whereas RAET1E and RAET1G contain transmembrane andcytoplasmic domains. Proteolytic cleavage of ULBP2 producestruncated and soluble forms that may counteract NKG2D-me-diatedtumorimmunesurveillance.Inthisstudy,wereportthat