FUT4 and glioblastoma: Further, Raychaudhuri et al. found that MDSCs represented 5.4 ± 1.8% of total cells in human GBM tumors; the majority were lineage negative (CD14–CD15–) eMDSCs, followed by PMN-MDSC (CD15+CD14–), and M-MDSC (CD15–CD14+) subtypes.