Cell viability assay by PI/Hoechst 33342 double nuclear staining for U251-pGFAP-HSVtk and U251-pCMV-HSVtk cells treated with GCV for 7 days.

The survivals of U251-pGFAP-HSVtk (A-F) and U251-pCMV-HSVtk (G-L) cells were determined by PI/Hoechst co-staining for cell nuclei after 5 μg/ml GCV treatment for 7 days. PI/Hoechst co-localized and condensed cell nuclei were identified at the 5th day and the 7th day of GCV treatment in both U251-pGFAP-HSVtk (D and E, arrows) and U251-pCMV-HSVtk (J and K, arrows) groups. No PI signal was detected after 3 days of recovery (F and L). Scale bar = 50 μm. (TIF)