LGALS9 and neoplasm: CSCs evade T-cell-mediated antitumor immune surveillance through various mechanisms, including suppression of T-cell activation, altered expression of major histocompatibility complex (MHC)-I at the transcriptional and posttranscriptional levels, downregulation of tumor-associated antigens (TAAs), and overexpression of ICs such as programmed cell death 1 ligand 1 (PD-L1) and Galectin-9 (Gal-9)8.