Fig. 1.

GBM cell killing effect of toTK1 in vitro. (A) Logarithmic graph showing the IC₅₀ of AZT in U87MG cells not transduced with toTK1. (B) Logarithmic graph showing the IC₅₀ of AZT in toTK1-transduced U87MG cells. (C) Graphs showing cell death in the coculture of the indicated proportion of toTK1-transduced and nontransduced U87MG cells upon exposure to AZT and treated with AGA to investigate the gap junction–mediated bystander cell killing effect. The theoretic line represents the cell death in the case where the only toTK1-expressing U87MG cells are killed. Note that the inhibition by AGA of the bystander killing is more pronounced at 10%–20% toTK1-expressing U87MG cells. Values are the means of 3 independent experiments. Error bars represent the standard errors.