Sushi domain containing 2 (SUSD2) is an 822-amino acid type 1 transmembrane protein, and it is composed of somatomedin b, adhesion associated domain in MUC4 and other proteins (AMOP), von Willebrand factor type D (VWFD) and sushi domains. These domains have been implicated in cell adhesion in other proteins, and consistently, SUSD2 has been shown to play a role in cell adhesion functions. SUSD2 shares the AMOP and VWFD domains with Mucin 4 (MUC4). In cancer, SUSD2 has been described as both protumor and antitumor depending on the type of cancer. The mouse homolog of SUSD2, Susd2/SVS-1, has been implicated in the regulation of neurite outgrowth during development. SUSD2 has also been identified as the antigen for the W5C5 antibody, which is used as a marker for the isolation of mesenchymal stem cells from human tonsil and bone marrow.