KLRK1 and colorectal carcinoma: For example, treatment of NSCLC and CRC cells with the anti-EGFR TKI gefitinib or erlotinib increased natural cytotoxicity of NK cells through upregulation of NKG2D ligands ULBP-1/-2 and MHC class I polypeptide–related sequence (MIC)A/B (113–116), and downregulation of PD-L1 expression (117).