MAPK9 and atrial fibrillation: JNK2 downregulates Cx43 and promotes diastolic calcium leak from the sarcoplasmic reticulum while simultaneously increasing the SR calcium content and creating a pro-arrhythmic environment [109,110] The AMPK pathway has also been implicated in AF [111], with the electrophysiological properties of atrial tissues in AMPK knockout mice showing an increase in atrial ectopic activity before the onset of AF, followed by delayed left atrial chamber enlargement [112,113].