Decorin is a protein coded for by the DCN gene. This protein is a component of the extracellular matrix, which is the intricate lattice of proteins and other molecules that forms in the spaces between cells. Decorin is found in the extracellular matrix of a variety of connective tissues, including skin, tendon, bone, and cartilage. Connective tissues support the body’s joints and organs. Decorin is involved in the organization of proteins called collagens. Collagens strengthen and support connective tissues throughout the body. Collagens also play an important role in the cornea, which is the clear outer covering of the eye. Bundles of collagen called fibrils must be strictly organized for the cornea to be transparent. Decorin ensures that these collagen fibrils are uniformly sized and regularly spaced.