JPH2 and atrial fibrillation: Previous studies demonstrated that junctophilin-2 (JPH2) that anchor the sarcoplasmic reticulum to T-tubules is the key regulator of Ca2+ influx between L-type Ca2+ channels (LCCs) and ryanodine receptors (RyRs) and E-C coupling in cardiomyocytes (31, 32), is reportedly associated with atrial fibrillation (33) and arrhythmias (34).