Immunocytochemical analysis of osterix expression in mesenchymal stem cell spheroids treated with an osteoblast-inducer reagent for 7 days. (A) Compared with monolayer mesenchymal stem cell (MSC; lower), positive cells (red) with anti- osterix antibody were increased in MSC spheroids (upper). 4′,6-diamidino-2-phenylindole (DAPI) was used to label nuclei (blue). Arrows, positive reaction in nuclei. Scale bars = 100 μm. (B) Significantly increased percentage of osterix positive cells was observed in MSC spheroids when compared to monolayer MSCs (*, p < 0.01).