Figure 1.

Heterozygous hMSH2 cells are phenotypically distinguishable from wild-type cells. Mean values of TMZ IC₅₀ (a), hMSH2 and hMLH1 steady-state protein levels (b), and mismatch repair efficiency (c) for each cell line are shown, along with the group mean values (filled squares) ± SE. The hMSH2 and hMLH1 protein levels in b were expressed as percentage of the levels found in the normals (see Materials and Methods). The dashed line in a represents the arbitrary cutoff value set to distinguish between normal and tolerant lines (see Results).