In a northern blot analysis, pBD-1 mRNA only expresses in tongue epithelial tissues from 4-5 week-old pigs. In RT-PCR analysis, pBD-1 message throughout the epithelia of the respiratory (from the nasal septum to lung) and gastrointestinal (from the esophagus to rectum) tracts. In addition, it is detected in thymus, liver, kidney, urinary bladder, spleen, lymph node, brain, testis, skin, heart, muscle, bone marrow, alveolar macrophages, peripheral blood neutrophils, and the umbilical cord. The only cells that do not express pBD-1 are peripheral blood mononuclear cells.