Used in research and development for targeted cancer therapies, particularly in studies involving the HER signaling pathway. Plays a role in assays to evaluate binding interactions with other HER family members like HER2 and EGFR. Supports the development of monoclonal antibodies and biosimilars by serving as a detection or capture antigen in ELISA and surface plasmon resonance (SPR). Employed in immunogenicity studies to assess immune responses against HER3-targeted therapeutics. Also utilized in protein-protein interaction studies and as a standard in quantification methods during biopharmaceutical production.