However, the mRNA expression of IL-1β, MMP-3 and MMP-13 in AF cells was significantly upregulated by stimulation of RANKL with IL-1β (1.0 ng/mL) (relative expression: RANKL 100 ng/ml + IL-1β (vs. RANKL 0 ng/mL+ IL-1β), IL-1β 2.86, p < 0.01; MMP-3 3.91, p < 0.05; MMP-13 3.66, p < 0.01) (Fig. 5a–c). This evidence concerns the gene MMP13 and atrial fibrillation.