Tumor-infiltrating NK cells can release cytotoxic T cells (CTL) to kill tumor cells (47), while TAM can secrete transforming growth factor-β (TGF-β), which can not only directly inhibit the activation of NK cells, but also indirectly inhibit NK cells by inducing the differentiation of Treg cells (48, 49). Here, TGFB1 is linked to neoplasm.