MMP13 and atrial fibrillation: However, ahRANKL-mAB treatment significantly suppressed the expression of IL-1β (Fig. 6a) and MMP-13 (Fig. 6e) by AF cells and that of MMP-3 by both AF and NP cells (Fig. 6c, d) upregulated by IL-1β (1.0 ng/mL) stimulation (relative expression: ahRANKL-mAB 1.0 μg/mL + IL-1β (vs. ahRANKL-mAB 0 μg/mL + IL-1β): AF: IL-1β 0.32 ± 0.10; MMP-3 0.37 ± 0.13; MMP-13 0.46 ± 0.13; NP: MMP-3 0.36 ± 0.06; p < 0.01, respectively).