Cell line panel in VeraTag™ lysate assays. Cartoons to the left of each graph depict the configuration of the antibodies in the corresponding assay. Experiments were performed using a duplicate eight-point titration of protein input. Points in the linear range were used to calculate RPA/mg protein. Gray bars represent signal from non-stimulated cells and black bars represent stimulation with 100 nM EGF for 10 minutes. A) HER1-HER2 heterodimer. B) HER1-HER1 homodimer. C) HER1 total. D) HER2 total.