Promotes osteoblast cell differentiation and terminal mineralization. Plays a role in inducing the cell cycle arrest via inhibiting CCND1 expression in all-trans-retinoic acid (ATRA) signal pathway. Interacts with NELL1; the interaction promotes osteoblastic differentiation and mineralization. Colocalizes with NELL1 on the nuclear envelope and the perinuclear region (PubMed:21723284). Weakly expressed in hematopoietic cell lines. Up-regulated by all-trans-retinoic acid (ATRA) in several tumor cell lines. Produced by alternative splicing of isoform 1. Produced by alternative promoter usage. Extended N-terminus. Extended N-terminus. Extended N-terminus. Truncated N-terminus.