CD4 and glioblastoma: Importantly, unlike CD39 (ENTPD1), another inhibitory marker shown to be elevated globally during gene expression analysis of glioblastoma tumor tissue, we demonstrated a significant inability of PMA and ionomycin stimulation to reduce TIM-3 on CD4+ and CD8+ T cells, as well as NK cells (but not Tregs), from glioblastoma patients.