Osterix affects NELL-1 and some bone marker genes expression in Saos-2 cells (A) and primary human osteoblast (hOB) (B).

Real time PCR analysis of Nell-1, OCN and OPN transcripts in Saos-2 cells transiently transfected with Control (pCtr) or Osterix expression vector (pOsx) at 2 days and 7 days (top panel). The effects with transcient transfection of Negative control siRNA (NC-siRNA) or Osterix siRNA mixture (Osx-siRNA) were revealed by Real time PCR analysis at 2 days and 7 days (bottom panel). (C) Diagram of the regulatory relationship between Runx2, Osterix and NELL-1. Runx2 positively regulates Osterix and NELL-1. Osterix negatively controlled NELL-1 expression in this study. NELL-1 was also shown to positively affect Runx2 through phosphorylation and negatively feedback on Osterix during osteogenesis.