(A, B) HCC827 cells treated with (A) increasing concentrations of gefitinib alone or in combination with PHA-665,752, in the absence or presence of HGF (50ng/mL), or (B) increasing concentrations of gefitinib alone or in combination with the indicated concentrations of HGF. Cell viability relative to untreated controls measured after 72 hours. Each data point represents the mean ±SD of 6 wells. (C) HCC827 cells were treated for 6 hours with 1μM gefitinib alone or in combination with the indicated concentrations of HGF. Cell lysates were immunoblotted to detect indicated proteins. (D) Cells were treated for 6 hours with gefitinib (HCC827, PC-9), PF00299804 (H1975), or lapatinib (BT-474, SKBR3), alone or in combination with HGF (50ng/mL). All drugs were used at 1μM. Cell lysates were immunoblotted to detect indicated proteins. *indicates cross-reaction by the p-EGFR antibody against p-HER2. Cell lines in which HGF rescued viability are labeled in blue, and cell lines in which HGF did not rescue viability are labeled in red. (E) HCC827-HGF xenografts in nu/nu mice treated with PF2341066, gefitinib, or their combination and tumors measured twice weekly. Some growth inhibiton was observed with gefitinib alone, however only combination treatment led to complete tumor shrinkage (p = 0.002). Each data point represents the mean ±SD for 5 mice. See also .