KLRK1 and hepatocellular carcinoma: The expression levels of activating receptors on NK cells were decreased: for example, such as CD16 in BT, multiple myeloma (MM), and CRC [86,87,88]; NKp46 in pancreatic tumor (PT-2), GC, CRC, acute myeloid leukemia (AML), and cervical tumor (CC-1) [89,90,91]; NKp44 in BT and AML [92,93]; NKp30 in BT, hepatocellular carcinoma (HCC), PT-2, GC, CRC, chronic lymphocytic leukemia, and CC-1 [86,89,90,91,94]; CD94/NKG2C in AML [91]; NKG2D in BT, lung tumor (LT), CRC, colon carcinoma (CC-2), PT-2, GC, and CC-1 [86,89,90,95,96]; CD244 in AML [91]; DNAM-1 in BT, CC-2, and AML [86,91].