KLRK1 and head and neck squamous cell carcinoma: Since these studies only investigated sMICA in NKG2D-dependent tumor immune escape, in the current study, we determined the levels of all the shed NKG2DLs (sMICA, sMICB, and sULBP1–3) in plasma samples of 44 HNSCC patients (patients’ characteristics are summarized in Table 1).