Anti-EGFR response of colorectal cancer lines with different <i>EGFR</i> GCN and <i>KRAS</i> status.

<p>(<b>a</b>) <i>EGFR</i> GCN SISH analysis of the different cell lines. (<b>b</b>) A western blot image showing the levels of EGFR protein in the different cell lines. α-tubulin was used as a control for equal loading. The cell viability of the different cell lines at varying concentrations of (<b>c</b>) cetuximab and (<b>d</b>) panitumumab. The results are given as percentage of viable cells in comparison to the non-treated cells (mean ± SE of five experiments). <b>(e)</b> Western blots showing EGFR pathway signaling molecules in the different cell lines. The cells were pretreated with the indicated amounts of cetuximab for 24 hours in medium containing 1% FBS and given egf (25 µg/ml) for 5 minutes before lysis. The indicated signaling molecules were analyzed with western blotting. GAPDH was used as a control for equal loading.