The present invention relates to an antigen-binding protein, preferably a monoclonal antibody, against annexin A2 (ANXA2), comprising (i) a heavy chain variable domain comprising a VHCDR1 of sequence GYSITSGYSWH, a VHCDR2 of sequence YIHYSGSTKYNPSLKS and a VHCDR3 of sequence GSNYGFDY; and (ii) a light chain variable domain comprising a VLCDR1 of sequence KSSQSLLYSNDQKNYLA, a VLCDR2 of sequence WASIRES, and a VLCDR3 of sequence QQYYIYPLT. Also provided is an ANXA2 binding protein comprising (i) a heavy chain variable domain comprising a VHCDR1 of sequence VYSITSGYSWH; a VHCDR2 of sequence YIHYSGSTKYNPSLKS, and a VHCDR3 of sequence GTDNAVDY; and (ii) a light chain variable domain comprising a VLCDR1 of sequence KSSQSLLYSSNQKNYLA, a VLCDR2 of sequence WASSRES, and a VLCDR3 of sequence QQYYIYPLT. The antibodies preferably bind to an N-linked glycan on ANXA2, and are internalised upon binding. They may be conjugated with cytotoxins and may be used in the treatment or detection of cancer.