F Primary neonatal mousecardiomyocytes stably expressing control or GPX1 shRNA by lentivirus infection were subjected to H2O2 (1 mM) for 30 minutes and then stained with 5 μM CellROX® Deep Red Reagent and analyzed by flow cytometry. * p = 0.0056; ** p = 0.0218, n = 3 wells per group, n = 3 wells per group. NS, not significant. 