NELL-1 binds to APR3 affecting human osteoblast proliferation and differentiation

► We constructed a cDNA library of Saos2 cells to identify NELL-1 interacting proteins. ► APR3 was identified as a direct binding protein of NELL-1 through phage display. ► The inhibitory effect of APR3 on osteoblast proliferation is enhanced by NELL-1. ► NELL-1 and APR3 binding can promote osteoblast differentiation and mineralization.