PLPPR1 and glioblastoma: Of all the markers that distinguish the GBM stem-like subtype from normal cells (orange, brown dots, and red crosses in Figure 2d), PTPRS, ATP1A3, MAGED4, NNAT, ASIC4, ITGA7, GPR56, HMP19, LPPR1, MAGED4B, and PTCHD2 are cell membrane markers.