ATF4 and atrial fibrillation: When we examined the significance of ATF4 or CHOP, we found that knockdown of ATF4, but not CHOP, remarkably inhibited Bz-induced CHOP upregulation (Fig. 6B) and partially but significantly attenuated the vacuolation-associated cell death induced by TrxR1 knockdown/Bz or AF/Bz (Fig. 6C, D).