Several other non-structural components with important cartilage ECM roles in development or osteoarthritis were also downregulated, including proteoglycan-related gene 4/lubricin (Prg4), procollagen C-endopeptidase enhancer 2 (Pcolce2), and Cytokine-like 1 (Cytl1). This evidence concerns the gene PCOLCE2 and osteoarthritis.