NCAM1 and neoplasm: Natural killer (NK) cells play a crucial role in the TME, contributing to various aspects of tumor regulation, including direct cellular eradication and the secretion of proinflammatory cytokines.[11] In humans, NK cells are primarily classified into 2 groups based on the expression levels of CD56 (NCAM1) and CD16 (FCGR3A): CD56dimCD16hi and CD56brightCD16lo.