Lumican also known as LUM is a member of the small leucine-rich proteoglycan (SLRP) family that includes decorin, biglycan, fibromodulin, keratocan, epiphycan, and osteoglycin. Lumican plays a crucial role in regulating collagen fibrillogenesis, which is essential for maintaining structural integrity of tissues. Lumican is predominantly found in corneal stroma and interstitial matrices of various tissues, including heart, aorta, skeletal muscle, skin, and intervertebral discs. Lumican′s ability to modulate collagen assembly into higher-order fibrils is vital for controlling diameter of these fibrils, thereby influencing tissue strength and elasticity. Notably, Lumican is present in extracellular matrix of human articular cartilage throughout life, with significantly higher levels observed in adults, indicating importance in cartilage health and function.