Lumican is a member of the small leucine-rich proteoglycan family that includes decorin, biglycan, fibromodulin, keratocan, epiphycan, and osteoglycin. The protein moiety binds collagen fibrils and the highly charged hydrophilic glycosaminoglycans regulate interfibrillar spacings.Lumican is the major keratan sulfate proteoglycan of the cornea but is also distributed in interstitial collagenous matrices throughout the body. Lumican may regulate collagen fibril organization and circumferential growth, corneal transparency, and epithelial cell migration and tissue repair. Lumican belongs to the family of small leucine-rich repeat proteoglycans. Recent studies have shown that lumican participates in the maintenance of tissue homeostasis and modulates cellular functions including cell proliferation, migration, and differentiation.