MMP13 and atrial fibrillation: Conversely, a significant increased release of MMP-1 after vitamin D treatment was observed in pooled cells (p = 0.004), NP (p= 0.03), and EP (p = 0.03) cells; this increase was also observed for MMP-3 in pooled cells (p = 0.03) and AF (p = 0.03) cells, whereas for MMP-13 in pooled cells (p = 0.005) only.