KLRK1 and esophageal squamous cell carcinoma: The application of NKG2D CAR-T cell therapy for ESCC is supported by the finding that MICA and MICB, family members of NKG2DLs, are significantly overexpressed in ESCC cells compared with adjacent normal tissues and that NKG2DLs are widely expressed on the surface of ESCC cell lines (19).