Figure 4 of Song, Mol Vis 2008; 14:161-170.

Figure 4. Quantitative real-time polymerase chain reaction analyses of p21WAF1/CIP1 mRNA expression in human corneal endothelial cells at various ages. Total RNA was isolated from HCECs of each group, and the first-strand cDNA were aynthesized from equal amounts of total RNA. Quantitative real-time PCR was performed to analyze p21WAF1/CIP1 mRNA expression. A shows the expression of p21WAF1/CIP1 from the eight age groups normalized to GAPDH mRNA. B demonstrates fold change in p21WAF1/CIP1 expression relative to the calibrator of the 20-year-old group. C is the comparison of the average level of p21WAF1/CIP1 mRNA expressed in HCECs between the young (≤ 30 years) and old (≥ 50 years) donors. Data are presented as mean±standard deviation and a p<0.05 is considered to be statistically significant. Results indicate no significant increase (p=0.875) in p21WAF1/CIP1 mRNA expression in HCECs from the old donors.