For example, in one embodiment where one is assaying for the ability to bind or compete with full-length DR3-V1 or DR3 polypeptide for binding to anti-DR3-V1 or anti-DR3 antibody, various immunoassays known in the art can be used, including but not limited to, competitive and non-competitive assay systems using techniques such as radioimmunoassays, ELISA (enzyme linked immunosorbent assay), ???san