Figure 2. Senescent endothelial progenitor cells (p16Ink4a+/CD34+) in human skeletal muscle after resistance exercise. (A) Representative immunohistochemical co-staining of muscle cross-sections (senescent cells indicated by arrows). Scale bar 55 μm. (B) Senescent endothelial progenitor cells decreased in human skeletal muscle after a single bout of resistance exercise, and to a greater extends under low protein supplemented condition. * Significant difference against Baseline, P < 0.05; † Significant difference against Low Protein, P < 0.05. Low protein: 14% protein; High protein: 44% protein in weight.