<p>A, number of senescent cells 3 days after treatment. Bars represent means±SEM (*<i>P</i><0.05 vs control; n = 6 experiments). B, p21 protein levels 24 hours after treatment. Bars represent means ±SEM (*<i>P</i><0.05 vs control; <sup>#</sup><i>P</i><0.05 vs H<sub>2</sub>O<sub>2</sub>; n = 3 experiments).</p