Background: The EGF receptor, ErbB2, and ErbB3 can interact to form dimers. Results: Analyses of these interactions show that ErbB3 interacts strongly with ErbB2 but weakly with the EGF receptor. All ErbB receptor interactions are enhanced by erlotinib and lapatinib. Conclusion: ErbB3 binds and is functionally affected by tyrosine kinase inhibitors. Significance: Tyrosine kinase inhibitors restructure the network of ErbB interactions.