PDK1 and glioblastoma: AKT3‐174aa encoded by circAKT3 negatively regulates the PI3K/AKT signalling pathway by interacting with phosphorylated pyruvate dehydrogenase kinase 1 (PDK1) in GBM; thus, the proliferation, radiation resistance and tumorigenic ability of GBM cells could be inhibited, which would provide benefits for the long‐term prognosis of patients.133