KLRK1 and thyroid gland carcinoma: PGE2 also suppressed the expression of the same NK receptors (NKp44, NKp30, TRAIL, and NKG2D) that were downregulated in NK cells cultured with culture supernatants of thyroid cancer cells (Figures 2F and 4B; Figure S4 in Supplementary Material), and reduced the levels of CD107a, reflecting the degranulation of cytolytic NK cells (Figure 4C).