Used as a recombinant protein antigen in immunoassay development and antibody screening, particularly in cancer research targeting hepatocellular carcinoma. Due to its modified form (S495A, S509A) and His tag, it offers improved stability and detection, making it ideal for studying GPC3-specific immune responses and for use in diagnostic kit development. Also employed in structural and functional studies to understand GPC3 interactions with antibodies or ligands in tumor environments.