Chondrogenic differentiation of CPSCs. After induction for 15 days, the cells in some areas aggregate to form clusters, and become larger. A–C, the induced cells were alcian blue positive. (100×) D RT-PCR revealed the expression of the chondrocyte-specific genes lane 1 Vimentin and lane 2 ACAN in cells from the induced group, whereas these genes were not expressed in cells from the control group (lane 4-5). GAPDH (lane 3 and Lane 6) served as the internal control.