The levels of NKG2D ligands (which can be recognized by other T-cell subsets, including γδ T cells and NK cells) (33) and of TRAIL receptors (which induce apoptosis in transformed cells but not in normal cells) (12) may therefore affect the susceptibility of the highly metastatic colon cancer cells to NK cells. Here, KLRK1 is linked to malignant colon neoplasm.