HSPA5 and glioblastoma: In the present study, combination of TMZ with vector carrying the HSVtk gene increased the cell death of GBM cell lines in vitro but the effect of combining TMZ with RGD4C/AAVP‐Grp78 was more pronounced than of TMZ combined with RGD4C/AAVP‐CMV, which could be explained by TMZ induction of gene expression from the Grp78 promoter.