MAPK1 and atrial fibrillation: The Annexin V/PI double-staining experiments showed that U0126, Z-VAD-FMK, and NS3694 were able to significantly reduce H2O2-induced apoptosis in AF cells (P < 0.05) (Fig. 4b), while JNK, p38, and caspase-12 blockers had no effect on the apoptosis in AF cells (Fig. 4b).