Co-treatment with GCV + ATO increases apoptosis within tumor sections. A) Representative fields of H&E stained sections from tumor explants 22 days post injection (original magnification of 200×). B) Total CNE1 < BX1 > nuclei and those displaying apoptotic changes were counted in 10 random fields from each group comprising multiple sections. C) Tumor xenograft sections from each of the treatment groups were stained for the immediate early EBV protein Zta (red) and activate Caspase-3 (green). Nuclei were stained with DAPI (blue) (original magnification of 200X).