Plays a role in the regulation of chondrocyte maturation and postnatal endochondral ossification. May inhibit cell growth stimulation induced by FGF2. Interacts (via the extracellular domain) with FGF2. Appears as reticular-like structures throughout the cytoplasm and adjacent to the plasma membrane (PubMed:21624478). In proliferation and hypertrophic chondrocytes, detected intracellulary and in the pericellular extracellular matrix. In primary spongiosa, detected only in the extracellular matrix (PubMed:28323137). Expressed only in cartilage, including nasal, knee epiphyseal and rib tissues (PubMed:21624478). In proliferation and hypertrophic chondrocytes, detected intracellulary and in the pericellular extracellular matrix. In primary spongiosa, detected only in the extracellular matrix (PubMed:28323137). At 16.5 dpc and 18.5 dpc expression is cartilage specific. In tracheal and nasal cartilage, expression is seen throughout all chondrocytes at a similar intensity while in other cartilage tissues undergoing endochondral ossification, intensity is strongest in proliferating and prehypertrophic stages. In knee epiphyseal cartilage, expression is detected from 12.5 dpc onwards, with significant up-regulation at 16.5 dpc and again at postnatal day 5. Expressed at least until 10 months of age. In chondrocytes, induced by BMP2. Mutants are born with the expected Mendelian frequency and show no differences in fertility, gross morphology or body weight (PubMed:28323137). Secondary ossification centers in knee epiphyses are smaller and growth plate maturation is disturbed, but total bone length is normal. Central proliferative and hypertrophic zones are enlarged with higher extracellular matrix volume and rounded chondrocyte morphology at postnatal days P10 and P22 (PubMed:28323137).