The present invention relates to isolated and/or recombinant nucleic acids which encode naturally occurring primate MAdCAMs, wherein said nucleic acid encodes the polypeptide shown in FIG. 1 (SEQ ID NO:2), the polypeptide shown in FIG. 2 (SEQ ID NO:4), or the polypeptide shown in FIG. 3 (SEQ ID NO:6). The invention further relates to recombinant nucleic acid constructs, comprising a nucleic acid which encodes a naturally occurring primate MAdCAM, wherein said nucleic acid encodes a polypeptide having an amino acid sequence as set forth in FIG. 1 (SEQ ID NO:2), FIG. 2 (SEQ ID NO:4), or FIG. 3 (SEQ ID NO:6); to host cells comprising such constructs, useful for the production of recombinant proteins; the use of nucleic acids and/or proteins in assays to identify inhibitors (e.g., antagonists) of primate MAdCAM function; and to antibodies reactive with primate MAdCAM, which are useful in in vitro methods, diagnostic and/or therapeutic applications.