We have recently discovered that Sialic acid-binding immunoglobulin-like lectin 9 (Siglec-9) is a leukocyte ligand of VAP-1 and a Gallium-68-labelled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-conjugated Siglec-9 motif peptide (68Ga-DOTA-Siglec-9) can be used for PET imaging of inflammation and cancer [21]. Here, AOC3 is linked to cancer.