BAX and atrial fibrillation: In AF cells, excessive mechanical stress can induce apoptosis via the Ca2+/Calpain2/Bcl-2-associated X protein (Bax)/caspase (Cas)-3 pathway [39], while in NP cells, it upregulates Bax, p53, p16, and p62 and downregulates B-cell lymphoma 2 (Bcl-2) and LC3-I/LC3-II [58].