Specific inhibition of EGFR does not result in radiosensitization of U251 and T98G cells. (A) Forty-eight hours after serum starvation, western blot analysis showed low levels of MGMT expression in U87 and U251 cells, and a high level of MGMT expression in T98G cells. U251 and T98G showed similar levels of p-EGFR expression. (B) Western blot analysis of U251 and T98G cells transfected with EGFR-specific or nonspecific siRNA. (C) Cells were plated for colony formation assay 48 h after transfection with EGFR-specific or nonspecific siRNA and irradiated as indicated. Points on survival curves represent mean surviving fractions from minimum three experiments performed in triplicate.