TREM1 and glioblastoma: TREM1+-cells were enriched in poly-morphonuclear PMN (up to 75%) and Mφ (up to 15%) fractions, and at a lesser degree were observed in the microglia fraction (up to 3%) following three weeks of the tumor development (Figure 3B, G for TRP and GL261 glioblastoma models, respectively).