KLRK1 and neoplasm: The spreading of NKG2D ligands through EVs could be considered a double-edged sword for MM cell immunosurveillance because on the one hand it could facilitate immunoevasion by inducing NKG2D downmodulation and NK cell fratricide but on the other hand it could abet NK cell recognition and killing of tumor cells cross-dressed with NKG2DLs.