KLRK1 and neoplasm: In addition to the upregulation of PD‐L1, the downregulation of NKG2D‐activating ligands such as UL16 binding protein 1 (ULBP1), ULBP2, ULBP3, major histocompatibility complex class I chain‐related molecules A and B (MICA and MICB) was reported to be another pathway for tumor cells to escape from NK cell‐mediated cytotoxic actions (Nausch and Cerwenka, 2008).