Masoudi et al. (2018) reported that miR-21 is a key factor in the pathogenesis of GBM, highlighting that overexpression of miR-21 results in a deregulation of crucial signalling pathways, such as PTEN/PI3K/AKT and TGF-β, contributing to tumour aggressiveness [49]. This evidence concerns the gene TGFB1 and glioblastoma.