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. Author manuscript; available in PMC: 2010 Jul 13.
Published in final edited form as: Oncogene. 2008 Feb 25;27(28):3944–3956. doi: 10.1038/onc.2008.19

Figure 5. HER2 and HER3 activity in cetuximab-resistant cells is EGFR-dependent.

Figure 5

A: Effects of EGFR knockdown on HER2 and HER3 activity. HC4 cells were plated and treated with the vehicle DMSO (control), 1μM erlotinib, 1μM gefitinib, 1nM of EGFR siRNA, 1 or 5 nM EGFR siRNA. 48 hours later protein was colleted and fractionated by SDS-PAGE and immunoblotted for the indicated proteins.

B: Effects of EGFR knockdown on proliferation of cetuximab-resistant cells. Cetuximab-resistant clone HC4 was plated and treated with control (DMSO), 100nM cetuximab, 1 μM erlotinib, 1 μM gefitinib, or 25 nM of EGFR siRNA. 72 hours later growth proliferation was measured as outlined in the materials and methods. *, P<0.05