Chen et al. identified the H19-derived immunoregulatory protein (H19-IRP) in glioblastoma (GBM), which recruits myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) through the activation of CCL2 and Galectin-9, thereby inducing T cell exhaustion. Here, LGALS9 is linked to glioblastoma.