Quantitative polymerase chain reaction analysis showing the relative mRNA expression levels of the bone formation-associated genes, ALP, OCN, RUNX2 and MSX2. Values were normalized against the mRNA expression level of the control group on day 1. *P<0.05, pMSCV-DLX2 group vs. pMSCV group (n=3). DLX, distal-less gene; ALP, alkaline phosphatase; OCN, osteocalcin; RUNX2, runt-related transcription factor; MSX, Msh homeobox; MSCV, murine stem cell virus.