AOC3 and arthritic joint disease: A soluble form of VAP-1 (sVAP-1) derived from the membrane-bound form is normally present at low levels in serum.14 VAP-1 activation is associated with many inflammatory conditions, including multiple sclerosis, atherosclerosis, dermatitis, inflammatory liver disease, and arthritis,14–17 making VAP-1 a potential target for in vivo imaging of inflammation.