KLRK1 and neoplasm: Ligands for NKG2D comprised human class I‐like molecules MICA, MICB, and ULBP, which are stress‐induced molecules expressed by tumors of epithelial origin and activate NK cell cytotoxicity through their NKG2D receptor.29, 30 Although we carried out immunohistochemistry using frozen sections as a preliminary experiment, evaluation of the expression of MICA, MICB, and ULBP2 in tumor tissue was challenging.