O6-Methylguanine-DNA methyltransferase (MGMT) tumor expression after combined treatment. After the last in vivo measurement (day 14), mice were sacrificed. MGMT expression in tumor receiving combined (a) DMSO/LV-CMVLuc-shControl, (b) DMSO/LV-CMVLuc-shMGMT2, (c) TMZ/LV-CMVLuc-shControl, and (d) TMZ/LV-CMVLuc-shMGMT2 was determined by immunostaining. Hematoxylin–eosin stainings (H&E) revealed necrotic areas (dashed line). Bars = 200 µm. CMV, cytomegalovirus; DMSO, dimethyl sulfoxide; TMZ, temozolomide.