Reverse transcriptase PCR techniques, revealed that most NKTCLtumor cells do express killer lectin type receptors (KLR) transcripts,including those for the CD94 and the NKG2 (most frequently NKG2A/B andNKG2D) receptors [80], a result that was confirmed by immunohistochemical stainings ontissue biopsies [76,77] and flow cytometry immunophenotyping of NKTCL and ANKCL cells [78]. This evidence concerns the gene KLRC1 and aggressive NK-cell leukemia.