Figure 3.

Effect of expression in wild-type cells of a dominant negative ATM fragment on (A) IGF-IR and EGFR levels and (B) clonogenic survival following IR. An SV40-transformed fibroblast cell line from an apparently normal individual (GM637) was transfected with a vector expressing a fragment of ATM containing the leucine zipper domain, which has been shown to function as a dominant negative protein (14). IGF-IR and EGFR levels were determined by Western blot in the 637 cells and in the cells transfected with the dominant negative leucine zipper fragment. Subclones 1 and 4 (LucZip1 and LucZip4) were chosen for analysis of radiation survival in comparison with the parental 637 cells.