Chitinase 3-Like Protein 2 (CHI3L2) is a 39 kDa secreted glycoprotein which belongs to the glycosyl hydrolase 18 family and the most closely related to human cartilage glycoprotein 39, which promotes the growth of human synovial cells as well as skin and fetal lung fibroblasts. Highest expression of CHI3L2 is in chondrocytes, followed by synoviocytes, lung and heart. It is not detected in spleen, pancreas, and liver. CHI3L2 may also be expressed in developing brain and placenta. Increased levels of CHI3L2 have been demonstrated in synovial fluids of patients with rheumatoid or osteoarthritis as well as in some other pathologies and in malignant tumors, particularly in glioblastomas. CHI3L2 may bind glycan structure with high affinity, but not heparin. It has has no chitotriosidase activity, but is likely to bind some type of glycan.