NTRK1 and glioblastoma: miR-34a is a significantly downregulated miRNA in GBM and has been shown to directly inhibit the expression of receptor tyrosine kinases and critical regulators of cell fate, such as MET, NOTCH1 and 2, CDK6, CCND1, and SIRT1, through which it directly regulates cell proliferation and survival as well as self-renewal and cell invasion in GBM [87,88,89,90].