Exhibits antimicrobial activity against Gram-negative bacteria and Gram-positive bacteria, with highest activity against Gram-negative bacteria (PubMed:9202117, PubMed:10837369). Antimicrobial activity against P.aruginosa seems to be salt-sensitive and is reduced with high salt concentrations greater than 25 mM (PubMed:10837369). Also exhibits antimicrobial activity against the yeast C.albicans (PubMed:9202117, PubMed:10837369, PubMed:30050988). Permeabilizes C.albicans cell membranes via targeting plasma membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP2), thereby leading to cell fragmentation and cell death (PubMed:30050988). Acts as a ligand for C-C chemokine receptor CCR6 (PubMed:10521347, PubMed:20068036). Binds to CCR6 and induces chemotactic activity of CCR6-expressing cells, such as immature dendritic cells and memory T cells (PubMed:10521347, PubMed:20068036). Monomer (PubMed:11300761). Homodimer (PubMed:10906336). Expressed in lung epithelial cells (at protein level) (PubMed:10837369). Expressed in foreskin, lung and trachea (PubMed:9202117). Lower expression in kidney, uterus and salivary gland tissue (PubMed:9202117). Expressed in epithelial cells of the respiratory tract, with higher expression in distal parenchyma of the lung, trachea, and tonsils, and lower expression in pharynx and adenoid, and low expression in tongue and larynx (PubMed:9831658, PubMed:10837369). Up-regulated by TNF, IL1B, Gram-negative and Gram-positive bacteria, C.albicans and bacterial lipopolysaccharides (LPS) (PubMed:9202117, PubMed:10837369). Up-regulated by inflammation in skin keratinocytes in epidermal tissue (PubMed:9831658). Belongs to the beta-defensin family. LAP/TAP subfamily.