Figure 5: Real-time PCR was used to evaluate mRNA level of chondrogenic marker genes [Sox9, collagen II (Col II), and aggrecan (AG)] and hypertrophic marker gene [collagen X (Col X)] in the pellets from SDSCs (A) and chondrocytes (B) after a 14-day serum-free chondrogenic induction. All 18S RNA normalized genes were shown as a ratio to the value of day 0 pellet cells from Plastic expansion. Significant differences are indicated as follows: * = p < 0.05; ** = p < 0.01; and *** = p < 0.001. Data are shown as average ± SD for n = 4.