IGFBP5 and glioblastoma: When visualizing EphA5, IGFBP5 and H2BK protein expression by fluorescence staining in solid human GBM samples, all molecules were stained in solitary cells or small cell groups within glial fibrillary acidic protein (GFAP, glial marker) positive tumor regions and (near) beside von Willebrand factor (vWF, endothelial marker) positively stained tumor vessels (Figure 1B).