Figure 6. Roxithromycin shows senolytic activity in senescent MRC-5 human lung fibroblasts. MRC-5 cells were pre-treated with BrdU for 8 days (to induce senescence), before they were exposed to Roxithromycin for another 5 days. After that, the SRB assay was performed to determine the effects of the drug on cell viability. Roxithromycin had a potent and selective effect on MRC-5, as it eliminated more than 50% of senescent cells after 5 days, at a concentration of 100 µM. However, Roxithromycin had no effect at 50 µM. These experiments were repeated at least 3 times independently, with very similar results. * p < 0.05.