This gene encodes a member the EWI subfamily of the immunoglobulin protein superfamily. Members of this family contain a single transmembrane domain, an EWI (Glu-Trp-Ile)-motif and a variable number of immunoglobulin domains. This protein interacts with the tetraspanins CD81 and CD9 and may regulate their role in certain cellular functions including cell migration and viral infection. The encoded protein may also function as a tumor suppressor by inhibiting the proliferation of certain cancers. Alternate splicing results in multiple transcript variants that encode the same protein.