KLRD1 and brain neoplasm: TGF-β is considered a pro-tumor cytokine (73, 74) that suppresses NK cell function by downregulating activating NK cell receptors (75–77) or their ligands on brain tumor cells (78) (Figure 1C), reducing NK cell proliferation and converting NK cells into pro-tumor ILC1-like cells (79), or upregulating immunosuppressive extracellular matrix TME components, such as the galectins (44).