Inhibition of BMPR2 or p-Smad1/5 decreased RUNX2 expression and reversed cell phenotype, while upregulation enhanced RUNX2 expression. BMPR2 or Smad1/Smad5 was interfered in NDCS-1, whereas overexpressed in SW1353 and HCS2/8. The BMPR2, RUNX2, and Smad1 expressions were detected by qRT-PCR (A, D). Western blot showed BMPR2, pSmad1/5, Smad1 and RUNX2 levels (B, E). The densitometric analysis of Western blot (C, F). (G) 100 pmol (siBMPR2-1) and 150 pmol (siBMPR2-2) BMPR2 siRNA had effect on Col2a1 expression in NDCS-1 cell. Mock: scrambled siRNA or empty vector; NC: normal cells; LDN193189: 5 nM was treat NDCS-1 for 24 h. n = 3, mean ± S.D. *p<0.05.