HSPA5 and glioblastoma: We also found that TMZ amplified the destruction of GBM cells in combination with RGD4C/AAVP‐Grp78‐HSVtk encoding the Herpes simplex virus type I thymidine kinase in the presence of ganciclovir (GCV); we used the HSVtk mutant SR39 (Black et al, 2001).