TGFB1 and glioblastoma: Glioblastoma stem cell (GSC) interactions with TAMs induce the secretion of transforming growth factor-β (TGF-β)1, favouring the conversion to pro-tumourigenic M2 macrophages through the preferential secretion of periostin, a chemoattractant, whose silencing through gene knockdown inhibited tumour growth in GSC-derived xenograft models [50].