Red arrows indicate the location of ERBB4 somatic mutations found in this screen. Red stars indicate ERBB4 mutants used in subsequent analysis. Boxes represent functional domains (I, Extracellular Domain Subregion I; II, Extracellular Domain Subregion II; III, Extracellular Domain Subregion III; IV, Extracellular Domain Subregion IV; Kinase, Tyrosine Kinase Domain).