DKK1 expression was increased during osteogenic differentiation. Osteoprogenitor cells were stimulated with osteogenic differentiation as indicated days. Differentiated cells were subjected to (A) Microarray analysis, (B) RT-qPCR for DKK1 and OCN mRNA levels, and (C) immunoblotting for DKK1 and OCN protein levels. OM, osteogenic media; D, days; DKK1, dickkopf-1; OCN, osteocalcin. *P < 0.05; **P < 0.01; ***P < 0.001; ns, not significant.