Lumican regulates collagenous matrix assembly as a keratan sulfate proteoglycan in the cornea and is also present in the connective tissues of other organs and embryonic corneal stroma as a glycoprotein. In normal unwounded cornea, lumican is expressed by stromal keratocytes. Our data show that injured mouse corneal epithelium ectopically and transiently expresses lumican during the early phase of wound healing, suggesting a potential lumican functionality unrelated to regulation of collagen fibrillogenesis, e.g. modulation of epithelial cell adhesion or migration. An anti-lumican antibody was found to retard corneal epithelial wound healing in cultured mouse eyes. Healing of a corneal epithelial injury in Lum ؊/؊ mice was significantly delayed compared with Lum ؉/؊ mice. These observations indicate that lumican expressed in injured epithelium may modulate cell behavior such as adhesion or migration, thus contributing to corneal epithelial wound healing.Rapid re-epithelialization is essential for restoration of homeostasis in injured tissues; impaired healing of injured epithelium increases the risks of infection and further damage underlying tissues (1, 2). The cornea provides an ideal model to evaluate interactions of migrating epithelial cells and the extracellular matrix of the underlying basement membrane during wound healing because epithelial injuries of the avascular corneal tissue heal in a bloodless wound field. Various specific proteins such as vinculin (3), keratins (4), CD44 hyaluronan receptors (5), and gelatinases and metalloproteinase inhibitors (6, 7) are up-regulated during corneal epithelial wound healing. These proteins are believed to modulate cell adhesion or migration.Lumican belongs to the family of small leucine-rich proteoglycans (SLRPs) 1 that includes keratocan, mimecan, decorin, biglycan, fibromodulin, epiphycan, and osteoadherin. In the cornea, lumican, keratocan, and mimecan are modified with keratan sulfate glycosaminoglycan chains comprising the keratan sulfate proteoglycans (KSPG) of the stromal extracellular matrix (8 -13). In normal unwounded mouse cornea, lumican mRNA is expressed in stromal keratocytes (14). Lumican KSPG is a key regulator of collagen fibrillogenesis, a process critical to corneal transparency. Mice lacking lumican show an age-dependent corneal opacity and a high proportion of abnormally thick collagen fibers in the corneal stroma (15).Lumican is also widely present as a non-or low-sulfated glycoprotein in connective tissues of many other organ systems, e.g. skeleton, heart, kidney, and lung (14, 16 -18). During mouse embryonic ocular development, lumican is synthesized by keratocytes; detected as a glycoprotein, not as a KSPG (19); and also transiently expressed by the corneal epithelium, neural retina, and epidermis (14). These observations suggest that epithelial tissues possess the capacity to express lumican under certain conditions. Several studies have demonstrated that SLRP proteins can modulate cellular behaviors, i.e. cell migration and prolifera...