Figure 3.

HER3 siRNA restores lapatinib‐mediated growth inhibition. (a) NCI‐N87 and OE19 were transfected with negative control siRNA or HER3‐targeting siRNA, or not transfected, for 72 h. Whole‐cell lysate was collected and protein lysates (20 μg) subjected to sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and Western blotting with the indicated antibodies. (b) Transfected cells were first incubated with dimethylsulfoxide (DMSO) or 1 μmol/L lapatinib for 30 min, then treated with or without 5 ng/mL HRG1 for 72 h. Cell proliferation was analyzed as described in Material and Methods. All cell proliferation data were averaged from quadruplicates of three independent experiments. Bars, SD. *t‐test, P < 0.001.