KLRK1 and colorectal carcinoma: In particular, CRC cells can express the NKG2D ligands (NKG2D-L) MICA and ULBPs, or the DNAM1 ligands (DNAM1-L) poliovirus receptor (PVR) and nectin-2: NKG2D–NKG2D-L and DNAM1–DNAM1-L interaction would lead to CRC cell recognition and killing by NK effector cells (26).