TCF7L2 and glioblastoma: The positive regulatory loop of TCF4N/p65 promotes glioblastoma (GBM) tumourigenesis and chemosensitivity: TCF4N upregulates NF‐κB activity by binding and promoting p65 S536 phosphorylation, nuclear‐translocation and stability; p65 promotes alternative splicing of TCF7L2 pre‐mRNA, resulting in an increase of TCF4N.