SMAD3 and atrial fibrillation: It showed that the expression of P-SMAD3/SMAD3 (Figure 7A and 7C), TGF-β2 (Figure 7A and 7D), TGF-β1 (Figure 7B and 7E), COL1A2 (Figure 7B and 7F), and COL3A1 (Figure 7B and 7G) was significantly up-regulated in the female LSP-AF group, but not in the male LSP-AF group, which further verified the TGF-β signaling pathway to play an important regulatory role in promoting fibrosis remodeling in the female LSP-AF group.