Effect of age on p53 pathway genes in human marrow stromal cells (hMSCs). (A): An age-related increase in p53, p21, and BAX gene expression was detected by RT-PCR. (B): Semi-quantitative RT-PCR analysis indicates significantly more expression of p53, p21, and BAX genes (normalized to internal control GAPDH) in hMSCs obtained from older subjects (n=9, ≥55-years), compared with hMSCs obtained from younger subjects (n=3, <50-years) (*p<0.01 and #p<0.05, Mann-Whitney test). Each lane indicates age and gender of the subject.