Figure 4

MCF-7 cells were infected with 10 ⁵ vp/cell of rAAV/ TRE/HSVtk/Tet-On. Twenty-four h after transduction, one group was exposed to 10 μg/ml of Dox and the other group without Dox administration. After 3 days, RNAs were extracted from the 2 groups and HSVtk gene expression was detected by RT-PCR with nested primers TK3/TK4 (a DNA fragment of 420 bp). For internal control, β-actin was co-amplified with HSVtk. The amplification product of HSVtk gene was observed in Dox inducement group but not in without inducement group. M: 100 bp DNA ladder; 1:group without induction; 2:group inducted with 1 g/L Dox