The expressions of proteins associated with proliferation and apoptosis were changed as follows: the expressions of Ki67, PCNA, and Bcl-2 showed a gradual decline, and the expressions of Bax, cleaved-caspase3/caspase3 and cleaved-caspase9/caspase9 had gradually risen in KLE cells treated by AF with varying concentrations (50, 70, and 100 μM) (Figure 2e). This evidence concerns the gene BAX and atrial fibrillation.