PTN and glioblastoma: In this study, we investigated the functional significance of the PTN–PTPRZ1 paracrine signalling in mediating the effects of TAMs on GSCs and tumour growth in GBMs, and identified the PTN–PTPRZ1 paracrine signalling axis as a critical molecular link between tumour-supportive TAMs and tumorigenic GSCs to facilitate GBM malignant progression.