SMAD2 and glioblastoma: Immunohistochemical analysis of rat brain GBM samples demonstrated that TEFT treatment markedly reduced the expression levels of TGF‐β (**p < 0.01), p‐SMAD2/3 (**p < 0.01) and p‐STAT3 (***p < 0.001), suggesting that TEFT effectively suppressed the TGF‐β signaling pathway (Figure 6B,C).