osteogenic differentiation of lentivirus-transduced USCs. (a) ALP activity in Lentiviral-BMP2 transduced USCs was significantly higher than that in Lentiviral-GFP transduced USCs and normal USCs. The deposited calcium was detected using Alizarin Red S (b, d and d) and von Kossa staining (e, f and g) at 14 days after transduction. (b and e) Normal USCs. (c and f) Lentiviral-GFP transduced USCs. (d and g) Lentiviral-BMP2 transduced USCs. For Alizarin Red S staining, the red color indicates calcium deposition (d); for von Kossa staining, dark patches indicate calcium deposition (g). Scale bar = 100 μm. #, P <0.05 (compared with normal USCs) and *, P <0.05 (compared with Lentiviral-GFP transduced USCs). ALP, alkaline phosphatase; BMP2, bone morphogenic proteins 2; USCs, urine-derived stem cells.