Figure 3

Differential ERK1/2 phosphorylation response to erlotinib treatment in HCC827 xenografts. Mice bearing xenografted tumors of HCC827 human lung adenocarcinoma cells were treated with one dose of water or 100 mg/kg erlotinib and sacrificed 24 h after treatment. Left panel, charge-CNIA of ERK phosphorylation in xenograft samples treated with water or with erlotinib. pERK1 and ppERK1 of mouse origin are resolved from the human isoforms and are shown in green box. Human pERK1 and ppERK1 are shown in red box, and arrows indicate that only the human isoform signals decrease with erlotinib treatment. The mouse stromal signal remains unchanged. Right panel, conventional Western is not able to detect the differential ERK isoform response between human cancer cells and mouse stroma cells and erroneously implies that ERK signaling by the drug is incomplete in the tumor cells [48].