Figure 9.

Neutralization of TGFα or MAPK function abolishes proliferation after irradiation of EGFR-CD533 cells in a cellular proliferation assay. Decreased proliferative rate of EGFR-CD533 cells in MTT assays over 1–4 d wherein cells were treated with either neutralizing anti-TGFα antibody (2 μg/ml) (A) or the MEK1/2 inhibitor U0126 (2 μM) (B). Cells were cultured in 24-well plates as in MATERIALS AND METHODS. Cells were pretreated with the indicated concentrations of anti-TGFα antibody or U0126 30 min before radiation exposure. Cells were exposed or not exposed to radiation and cultured for 1–7 d in the presence of drug or antibody. MTT assays were performed on each day as described in MATERIALS AND METHODS, and growth curves were plotted to determine the growth potential of treated cells. Data are shown from the means of 12 data points ± SEM from a representative experiment (n = 2).