Fig. 3

IHC staining, analysis of other genetic markers, and Kaplan–Meier survival analysis identified GSTM1 as a prognostic marker in glioblastoma. a A representative IHC staining picture of GSTM1 in GBM tumor samples. The upper panels showed high expression (++ to +++) of GSTM1 under different magnification, whereas the lower panels showed low expression (− to +) of GSMT1. Scale bars were shown in each panel. b Bar graph showed the number of GSTM1 positive cells in the tumor tissue vs. normal brain tissue under high power field (A representative picture was shown in Additional file 1: Fig. S2). The numbers of tumor tissue (N = 26) and normal tissue (N = 22) used were shown. A statistical significance (p < 0.001) between tumor and normal tissues was shown. c The expression of GSTM1 was not correlated with sex, age, MGMT promoter methylation status, or IDH1 mutation status. d A Kaplan–Meier survival analysis of 125 GBM patients according to the expression of GSTM1 showed that high GSTM1 expression was associated with shorter survival (log rank and Wilcoxon analysis)