Chitinase-3-like protein 1 (CHI3L1), also known as YKL-40, is a secretedglycoprotein that is approximately 40kDa in size that in humans is encoded by the CHI3L1gene.[5][6][7] The name YKL-40 is derived from the three N-terminal amino acids present on the secreted form and its molecular mass. YKL-40 is expressed and secreted by various cell-types including macrophages, chondrocytes, fibroblast-like synovial cells, vascular smooth muscle cells, and hepatic stellate cells. The biological function of YKL-40 is unclear. It is not known to have a specific receptor. Its pattern of expression is associated with pathogenic processes related to inflammation, extracellular tissue remodeling, fibrosis and solid carcinomas[8] and asthma.[9]
^Rehli M, Krause SW, Andreesen R (July 1997). "Molecular characterization of the gene for human cartilage gp-39 (CHI3L1), a member of the chitinase protein family and marker for late stages of macrophage differentiation". Genomics. 43 (2): 221–5. doi:10.1006/geno.1997.4778. PMID9244440.