SLC9A9 and glioblastoma: NHE9 is a master regulator of cargo delivery and recycling by mediating inside‐out control of oncogenic signalling in glioblastoma.4, 8 Increased cell surface receptor densities are the hallmark of GBM9+ tumours.4, 8 This gain of function observed in GBM9+ tumours formed the basis for our study directed at identifying an effective therapeutic strategy for GBM9+ subset of tumours.