NCAM1 and nasopharyngeal carcinoma: Further immunohistochemistry showed that compared with the normal nasopharyngeal mucosa tissue, the expression of CD56 (the marker of NK cells) and granzyme B (one of the key cytotoxic effectors of NK cell) decreased, while the expression of TIGIT and LAG3 increased in the NK-NPC tissue, indicating that the NK mediated cytotoxic signaling pathway was inhibited.