Chemotactic factor that mediates lymphocytes recruitment to epithelia through binding and activation of the G-protein coupled receptor GPR15 (PubMed:28900043, PubMed:28936214). May be a tumor suppressor; together with SUSD2 has a growth inhibitory effect on colon cancer cells which includes G1 cell cycle arrest (PubMed:25351403). Has antimicrobial activity against Gram-positive bacteria, including Staphylococcus aureus and Actinomyces spec., and Mycoplasma hominis and lentivirus (PubMed:25585381). Interacts with SUSD2; the interaction is direct. Expressed at high levels in colon, and cervix and at moderate level in tonsil (PubMed:25585381, PubMed:28900043). Highly reduced expression in primary colon cancer tissues compared with that in adjacent tissues (PubMed:25351403). Highest levels of expression detected in stomach and colon; expressed in epithelium of skin and esophagus, and in some tumor and/or tumor adjacent tissues (TAT), including TAT of esophagus cancer, hepatocellular carcinoma (HCC), squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and invasive ductal carcinoma (IDC) tissues (at protein level) (PubMed:25585381).