MTOR and central nervous system cancer: The expression of glutathione S‐transferase A4 (GSTA4) in glioblastoma and the effect of curzerene on the expression of GSTA4 and matrix metalloproteinase 9 and the activation of the mTOR pathway were detected by Western blotting and RT‐PCR, and the effects of curzerene treatment on glioma malignant character were detected by cell biological assays.