PDGFA and atrial fibrillation: In AF patients (14), mast cells may induce cardiac fibroblasts to increase collagen production by secreting PDGF-A, resulting in atrial fibrosis and AF CXCL1 may mediate inflammatory responses through the NF-κB (nuclear factor-κB), TGF-Smad 2/3 signaling pathways, among which TGF-β is an important pro-fibrotic cytokine.