UCMA is a secreted cartilage-specific protein that was discovered in a screen for differentially expressed genes in retinoic acid-treated mouse chondrocytes. It was also identified in a human chondrocyte EST screen for candidate genes of skeletal dysplasias. UCMA expression is thought to parallel that of collagen II with its expression decreasing with maturation chrondrocytes mature. UCMA is processed by a furin-like protease into two fragments, an amino-terminal fragment and a carboxy-terminal fragment (UCMA-C). Application of recombinant UCMA-C to primary osteoblasts, mesenchymal stem cells, and MC3T3-E1 pre-osteoblasts interferes with their osteogenic differentiation, but does not affect expression of chondrocyte-specific genes or chondrocyte proliferation, suggesting that UCMA may be involved in the negative control of osteogenic differentiation of osteochondrogenic precursor cells. At least two isoforms of UCMA are known to exist.